Sudowoodo is a static encounter on Route 36 in all three games. In order to trigger the battle, the player needs to obtain the SquirtBottle from the flower shop, which is only available after beating Whitney.
Easy to meet, yet rather hard to catch, and with a single evolutionary stage of a type that is rarely seen not in conjunction with Ground, this Pokémon is fairly unique. Since Geodude is very common in Johto and covers the physical tank role very well, as well as learning Earthquake by level-up - a move that is only accessible to Sudowoodo via TM - most nuzlockers will not look hard into getting another Rock-type, and thus often miss out on the amazingness that is Sudowoodo. While the movepool may be more shallow than Golem's, Sudowoodo is very powerful early on and can also hold its own throughout the game, thanks to being a single stage Pokémon with a decent initial moveset, and its pure typing and not-so-bad special bulk make it sturdier than it might look, capable of enduring much pain without going down. Thanks to the type distribution and the kind of threats Johto poses to nuzlockers, Sudowoodo can actually cover a niche role in most teams.
Rival (Burned Tower): Sudowoodo easily 2HKOs Haunter and OHKOs Magnemite with Dig. Rock Throw 2HKOs Zubat, though its Confuse Ray may delay its downfall; do not fight Zubat with a Curse hovering over Sudowoodo's head. Quilava is 2-3HKOed with Rock Throw as well, but both Bayleef and Croconaw outdamage and outspeed Sudowoodo.
Gym #4 - Morty (Ecruteak City, Ghost-type): Dig can 2HKO Gastly and both of the Haunter, bypassing Curse even if they do use it. Against Gengar, Dig is only a 3HKO, but Sudowoodo is still capable of taking it on and win if there is no Curse laid upon it; Gengar does know Mean Look, however, and also the Hypnosis and Dream Eater combination. Since Sudowoodo is slower than it, it needs to be kept awake at all times.
Eusine (Cianwood City, Crystal only): Drowzee is 2-3HKOed by Return if at maximum power, but can also be simply 3HKOed with Rock Throw; its Hypnosis is an annoyance, but Dream Eater deals relatively little damage. Haunter is 2HKOed by Dig, but Electrode 2-3HKOs with Thunder and must not be fought.
Gym #5 - Chuck (Cianwood City, Fighting-type): Return actually outdamages Primeape's Karate Chop, 3HKOing it cleanly; Primeape, by contrast, only 4HKOs. Poliwrath must be avoided, or it will 2HKO Sudowoodo with Surf.
Gym #6 - Jasmine (Olivine City, Steel-type): Dig OHKOs both of the Magnemite, but there is nothing Sudowoodo can do against Steelix's 2HKO Iron Tail. The ace should be fought by a better suited counter.
Rocket Executive battle #1 (Team Rocket HQ): Zubat is OHKOed by either Rock Throw or Rock Slide, and Koffing is 2HKOed easily with Dig. Sudowoodo's strongest move will also averagely 2HKO Raticate (or 3HKO at worst), whether that is Rock Slide or Return.
Rocket Executive battle #2 (Team Rocket HQ): Dig 2HKOs Arbok and Rock Slide 2-3HKOs Gloom; the latter only has Absorb for STAB, and Sudowoodo takes relatively little damage from it. Murkrow is OHKOed by Rock Slide.
Gym #7 - Pryce (Mahogany Town, Ice-type): Seel is 2-3HKOed by Rock Slide; Dewgong is 2HKOed. Neither of them has Water STAB, and Aurora Beam is relatively weak coming off both of them. Only Piloswine must be avoided, as its Blizzard outpowers all of Sudowoodo's available moves.
Rocket Executive battle #3 (Goldenrod Radio Tower): Dig is an average 2-3HKO against Koffing, and always 4HKOs Weezing. Sudowoodo's Normal resistance comes in handy in this battle, as it cannot be killed even by a critical Explosion from Weezing.
Rival (Goldenrod Underground): Golbat is easily 2HKOed by Rock Slide, and may only really use Confuse Ray to delay its demise. Dig OHKOs Magnemite and 2HKOs Haunter. Rock Slide is a 1-2HKO against Sneasel and Quilava, and can also 3-4HKO Meganium, now that it lacks Grass STAB; Feraligatr still knows Water Gun, so Sudowoodo would lose against it.
Rocket Executive battle #4 (Goldenrod Radio Tower): Dig 2-3HKOs Arbok; Rock Slide can 3-4HKO Vileplume, depending on Absorb recovery as well as damage variation, but Sudowoodo will win either way, since Absorb is very underpowered compared to Rock Slide. Murkrow is still destroyed by Rock Slide.
Rocket Executive battle #5 (Goldenrod Radio Tower): Houndour is OHKOed by Rock Slide, Houndoom is 2HKOed. Koffing can be 2-3HKOed with Dig instead. None of them are dangerous.
Suicune (Bell Tower, Crystal only): No. Suicune's BubbleBeam 2HKOs Sudowoodo without any chance for a counterattack.
Gym #8 - Clair (Blackthorn City, Dragon-type): The lead Dragonair can 3HKO Sudowoodo with Surf, but the other two only know Thunderbolt and Ice Beam respectively, thus Sudowoodo's Rock Slide will 3HKO them. Kingdra's Surf is also to be avoided, as it borders on the OHKO.
Rival (Victory Road): Sneasel is OHKOed by Rock Slide, whereas Golbat is 1-2HKOed and Kadabra is 2HKOed; Haunter and Magneton are OHKOed by Earthquake. Typhlosion is 2HKOed by either Rock Slide or Earthquake, and relatively powerless against Sudowoodo; Meganium and Feraligatr, on the other hand, both beat Sudowoodo with their respective STAB moves.
Elite Four Will (Indigo Plateau, Psychic-type): Rock Slide is a highly likely OHKO against the lead Xatu, though the ace Xatu will most likely be 2HKOed; at any rate, Sudowoodo does not fear their Psychic. Jynx is also OHKOed by the move. Fighting against Exeggutor is not recommended; while it lacks Grass STAB, it knows Reflect and can quickly outdamage Sudowoodo with Psychic by putting it up. Slowbro can be 3-4HKOed on average without any Curses used, and its Psychic is a 4HKO; at worst, Sudowoodo can win by stalling it out.
Elite Four Koga (Indigo Plateau, Poison-type): Ariados is 1-2HKOed by Rock Slide, whereas Venomoth is always OHKOed, and Crobat is 2HKOed. Ariados' Special Attack is very low, so Sudowoodo does not need to worry about its Giga Drain. Forretress is only a 4HKO, but its only offensive moves are Normal-typed and Explosion cannot kill Sudowoodo, even if it crits. Muk is easily 2HKOed by Earthquake without any Acid Armor setups, but can be worn down even if it does set up, as its only directly damaging move - Sludge Bomb - deals little to no damage to Sudowoodo.
Elite Four Bruno (Indigo Plateau, Fighting-type): Hitmontop is 3HKOed by Earthquake, or even 2HKOed if it opts for Dig; it knows no Fighting moves. Earthquake can also 3HKO Hitmonchan, whose Mach Punch only KOs in at least five turns. Return is guaranteed to 2HKO Hitmonlee, and Earthquake also can, but with a lesser certainty; Hitmonlee's Hi Jump Kick is a 3HKO bordering on a 2HKO, however, so only a fully healthy Sudowoodo can beat it, and assuming that Hitmonlee does not use Swagger instead, which makes the matchup entirely reliant on luck unless Sudowoodo is holding a Bitter Berry. Sudowoodo's Earthquake also outmatches Onix's own, 2HKOing it.
Elite Four Karen (Indigo Plateau, Dark-type): Umbreon relies on Mean Look, Confuse Ray and Sand-Attack to beat its enemies; Sudowoodo can KO it in an average of four turns, but may need to be healed a few times in the process. Holding a Bitter Berry will simplify this task. Rock Slide OHKOs Murkrow, but Vileplume outmatches Sudowoodo by far with its Petal Dance. It is advised to not fight Gengar unless Sudowoodo can outspeed it; Earthquake is a 2HKO, but Gengar knows Destiny Bond and can easily take Sudowoodo down with it, though a paralysed Gengar will be easily outsped. Lastly, the ace Houndoom can be 2HKOed by both Rock Slide and Earthquake; unless PP are an issue, Earthquake should be preferred, due to having greater accuracy.
Champion Lance (Indigo Plateau, Flying-type): Sudowoodo should not fight Gyarados; although Rock Slide is a certain 2HKO against it, Gyarados' Surf is an equally likely 2-3HKO, which would put Sudowoodo in serious danger. On the other hand, Rock Slide easily 2HKOs the two level 47 Dragonite; the level 50 one is a variable 2-3HKO, however, and its Outrage is always a 3HKO, so Sudowoodo may need to switch out on the second turn if the KO is not scored. Charizard and Aerodactyl are easily OHKOed and 2HKOed, respectively.
From this point onwards, you can fight the gyms in any order, though you will need to retrieve the Machine Parts from the Cerulean City gym before you have access to the earlier portion of Kanto. Feel free to anticipate or postpone any battles as needed.
Gym #9 - Brock (Pewter City, Rock-type): Sudowoodo's Earthquake 2HKOs Graveler, Rhyhorn and Onix; the first two can only 3HKO with their own Earthquakes, whereas the third lacks Ground STAB altogether and is non-threatening. Both Omastar and Kabutops, however, would 2HKO Sudowoodo with Surf; they must be avoided.
Rival (Mt. Moon, optional): Rock Slide still OHKOs Sneasel and 1-2HKOs Golbat, depending on Sudowoodo's level and stats. Magneton is OHKOed by Earthquake, which also scores a 1-2HKO against Gengar. Alakazam can be 2HKOed with either Rock Slide or Earthquake, or even Return if Sudowoodo still knows the move. Rock Slide and Earthquake both 2HKO Typhlosion as well, but neither Meganium nor Feraligatr can be fought by Sudowoodo.
Gym #10 - Misty (Cerulean City, Water-type): All of Misty's Pokémon outspeed and 2HKO Sudowoodo, which should not enter the battlefield at all.
Gym #11 - Lt. Surge (Vermilion City, Electric-type): Sudowoodo can OHKO all of Lt. Surge's team with Earthquake after one Curse, which it can use against Raichu, as its Thunder only 3HKOs. Sudowoodo needs to be above half health to fight against Electabuzz, however, as its Thunder borders on a 2HKO.
Gym #12 - Erika (Celadon City, Grass-type): Sudowoodo can 1-2HKO Jumpluff with Rock Slide, but Erika's other Pokémon all outpower it with their Grass STAB, and they should not be fought.
Gym #13 - Janine (Fuchsia City, Poison-type): Rock Slide is a 2HKO against Crobat and an OHKO against Ariados and Venomoth. Earthquake is a 2HKO against both of the Weezing, whose Explosion barely tickles Sudowoodo.
Gym #14 - Sabrina (Saffron City, Psychic-type): Sudowoodo is hopeless against Espeon and Alakazam, both of which outspeed and can deal about as damage as Sudowoodo's Rock Slide. Alakazam and Mr. Mime also have Reflect, and are likely to put it up to further reduce damage intake. Overall, it is better for Sudowoodo to not participate in this battle.
Gym #15 - Blaine (Seafoam Islands, Fire-type): Earthquake OHKOs Magcargo and 2HKOs Magmar and Rapidash. It is recommended over Rock Slide even for the last two, as Rock Slide cannot OHKO them (except Magmar, but the chance is small), and Earthquake is a more accurate move.
Gym #16 - Blue (Viridian City): Rock Slide 2HKOs both Pidgeot and Arcanine, but that is the extent of Sudowoodo's help in this battle; Rhydon 2HKOs it with Earthquake, Gyarados either 2HKOs with Hydro Pump or OHKOs after Rain Dance, Exeggutor's SolarBeam is an OHKO and only requires one Sunny Day turn to set up, and Alakazam's Reflect will quickly render Sudowoodo's moves next to powerless against its Psychic.
Rival (Indigo Plateau, optional): Rock Slide is a 1-2HKO against Sneasel and still also 2HKOs the now-evolved Crobat. Earthquake OHKOs Magneton and 2HKOs Gengar. Alakazam is 2HKOed by Rock Slide, but only if Reflect is down; since Alakazam is faster, it is likely to use Reflect before long, possibly even the first turn, and if that is the case Sudowoodo needs to switch out, as it would get severely outdamaged by Psychic. Typhlosion is an easy 2HKO by Rock Slide, but Meganium and Feraligatr would win with Giga Drain and Surf respectively, and must be avoided as such.
Red (Mt. Silver): Pikachu can be OHKOed easily with Earthquake, unless it uses Charm; depending on the number of usages of this move, taking it down will require proportionally more turns. Espeon outmatches Sudowoodo, 3HKOing with Psychic and potentially throwing Reflect in the mix, which severely nerfs Sudowoodo's attacking power. Snorlax or Charizard can be used to set up Curse against; neither of them deals much damage, as Sudowoodo resists all of their moves, though even after a full +6 Sudowoodo is not guaranteed to one-shot all of Red's Pokémon. Snorlax is 1-2HKOed, which is a non-issue as its Body Slam is ridiculously weak, and Charizard is OHKOed by Rock Slide no matter the amount of setups, but Venusaur and Blastoise are 1-2HKOs as well and they can each 2HKO Sudowoodo with Giga Drain and Surf respectively; if Sudowoodo does not manage to OHKO them, it may need to withdraw from battle, particularly if they use their first turn to set up Sunny Day or Rain Dance: in that case, they would OHKO on the following turn (Venusaur knows SolarBeam).
Sudowoodo starts with a decent set of Rock Throw, Mimic, Flail and Low Kick when caught. While Mimic and Flail are not that useful, the other two provide great starting coverage; Low Kick is not weight-based in this generation, and instead deals a fixed base 50 power damage. Rock Throw is not too powerful for a STAB move, but it gets upgraded to Rock Slide not long after capture, at level 28. This is a move Sudowoodo will want to keep for the whole game, as there is no better Rock STAB available. Faint Attack comes at 37, but is not really worth learning due to Sudowoodo's really bad Special Attack; lastly, Slam comes at 46, a move Sudowoodo will never need due to both Strength and Return outclassing it by far.
TMs help broaden Sudowoodo's coverage, providing the ever-useful Earthquake which, however, is not accessible until Victory Road. In the meantime, Sudowoodo can be taught Dig instead, if Ground coverage is needed. DynamicPunch is for those who either want to live dangerously or are packing a lot of X Accuracy (which makes moves never miss in this generation), but is nevertheless an option. Curse is also great for players who continue their run through Kanto, as Sudowoodo's good bulk actually permits a decent setup. Consider Rest too, if the nuzlocke ruleset limits or forbids the usage of healing items. Swagger is also fairly good, since its Defense is high, but Sudowoodo has better options available.
Recommended moveset: Curse, Rock Slide, Earthquake, Return
Grass-types: Although Grass-types in general are by no means excellent in Johto, they are the most helpful paired with Sudowoodo, since they compensate for three of its five weaknesses. Dual Grass/Poison Pokémon should be avoided, since they lose the necessary Ground resistance.
Flying-types: Flying provides an additional Ground immunity, as well as a means of hitting Fighting-types with super effective damage. For this purpose, it is essential to have a Flying-type that learns good Flying STAB, and has good Attack to support it; Flying-types that retain their Fighting resistance should also be preferred over Normal/Flying-types.
Special tanks: Sudowoodo is fairly lacking in special bulk, even though its lack of double weaknesses makes it a little better than Pokémon like Golem. It will still not be able to take strong special hits, unless they are not very effective, so a proper special tank should be designated.
Fast hitters: Sudowoodo is very, very slow. It is strongly recommended to offer it support through a fast sweeper, because should there ever be a need to hit first in a fight, Sudowoodo will simply not manage to do so.
Sudowoodo's Steel weakness may optionally be supplemented with a Fighting-type, since Fighting-types are ideal for this role; their weaknesses do not overlap with Sudowoodo's. However, given how rare Steel moves are, this addition to the team is not strictly necessary.
Minimum stats are calculated with 0 EVs, IVs of 0, and a hindering nature, if applicable.
Maximum stats are calculated with 252 EVs, IVs of 31, and a helpful nature, if applicable.
How good is Sudowoodo in a Nuzlocke? Very good, much more so than one would expect. It provides an original alternative to the usual Geodude liners, which has the perks of being a sure-fire encounter and also lacks the crippling dual weaknesses to Grass and Water, making it essentially impossible to OHKO. It tanks the dangerous Explosions of the Team Rocket members like there is no tomorrow, and has no real bad matchups overall in the whole game, including the postgame.
Weaknesses: Fighting, Ground, Steel, Water, Grass
Resistances: Normal, Flying, Poison, Fire
Neutralities: Rock, Bug, Ghost, Electric, Dark, Psychic, Dragon, Ice