Water-types are always extremely useful in Nuzlockes, and the Squirtle line is no exception. With fantastic defenses as a Blastoise, strong and reliable STAB in Surf, and good coverage, the Squirtle line is very useful throughout the game and is quite easy to use. With only two weaknesses to relatively uncommon attacking types, it is quite easy to keep alive. Squirtle has a relatively good level-up movepool and also has great TM options such as Ice Beam, Brick Break, Dig, and Earthquake. Overall, the Squirtle line is amazing for a Nuzlocke, as its bulk, good movepool, and useful defensive typing allow it to stay useful throughout the entire game. It’s very easy to use, and unless you’re extremely unlucky, it’s relatively easy to keep alive as well.
Rival (Oak's Lab): Squirtle's high defenses might allow a win without use of Potion, particularly if Bulbasaur's AI malfunctions and spams Growl rather than actually attacking. Tail Whip also acts to counter Growl.
Rival (Route 22, optional): While Pidgey is easy to handle, Bulbasaur's Leech Seed may cause difficulties if the fight drags on. On the bright side, it doesn't have an actual STAB move to use against you, which puts you at an advantage over the other Starter-Rival matchups at this point.
Gym #1 - Brock (Pewter City, Rock-type): Bubble (or Water Gun, if you have it) should see you to victory over Brock's Rock/Ground types with ease.
Rival (Cerulean City): While Pidgeotto, Rattata, and Abra should be manageable, Bulbasaur now has Vine Whip. Use a different Pokémon against it if at all possible.
Gym #2 - Misty (Cerulean City, Water-type): Staryu shouldn't be too hard (due to Wartortle's defenses and Water Pulse resistance), and Starmie can be handled with Bite. Beware of confusion.
Rival (S.S. Anne): Pidgeotto is annoying, with Sand-Attack spam, but nothing too powerful. Bite takes care of Kadabra. Beware Raticate and its STAB Hyper Fang, but Wartortle's defences should prevent it from taking more damage than you can heal. Ivysaur is the real danger here - do not use Wartortle unless absolutely forced to do so, as STAB super-effective Vine Whip is not a laughing matter.
Gym #3 - Lt. Surge (Vermillion City, Electric-type): The insane and/or overleveled might want to play fast and loose with Dig. Unless you're doing a Monolocke, though, why don't you just go and catch a Diglett?
Rival (Pokémon Tower): Pidgeotto is nothing to write home about; those who went to Celadon first might want to snag an Ice Beam TM from the Game Corner for a good laugh. Actually, snagging an Ice Beam TM is a good idea in general - you'll want it later. Growlithe is good for cheap Exp. and Kadabra is still Extra Dead Enchanted versus Bite. The major dangers are Gyarados and Ivysaur. Some might want to challenge the latter with Ice Beam, but why toy with your starter's life like that?
Giovanni (Rocket Hideout, Ground-type): Onix and Rhyhorn are laughingstocks against any decent Water move. The combination of Kangashkan's base 95 Attack and STAB Mega Punch poses a danger, but Wartortle can boost its Defense via Withdraw while mowing through the two prior opponents - if you still have Withdraw.
Gym #4 - Erika (Celadon City, Grass-type): STAB super-effective Giga Drain from high-Special-Attack Pokémon? Keep Wartortle far, FAR away from this Gym. If you absolutely must, Ice Beam IS super-effective against Erika - but even Monolockers have other options. At least Gyarados is neutral to Grass.
Gym #5 - Koga (Fuchsia City, Poison-type): Levitate prevents Dig abuse, sadly. Running over to the Safari Zone and picking up Surf will ease your way in this fight, but using strong Special-based attacks should carry you through. Watch out for Self-Destructs by the Koffings.
Fighting Dojo (Saffron City, Fighting-type): Blastoise is neutral to all attacks, and sports 100 base Defense. Hitmonchan's laughable 35 base Special Attack prevents Thunderpunch from being a threat. The Hitmons both have high Special Defense, but their HP stats are lacking. Multiple Surfs should take them out with ease.
Rival (Silph Co.): Swamp Pidgeot and Growlithe with Surf. Alakazam's only attacking move is Future Sight - Bite or Surf it to death (STAB Surf is actually stronger than super-effective Bite, but Bite has that handy 30% flinch chance, if you’re faster and are feeling lucky). Gyarados is distinctly weaker without Thrash, and now has a top damage rate of 40 HP (Dragon Rage). Venusaur now sports Razor Leaf - if you've been somehow taking it on with your starter prior to this, DON'T.
Giovanni (Silph Co., Ground-type): Surf your way through this one. Kangaskhan is still dangerous, but less so against Blastoise than it was against Wartortle.
Gym #6 - Sabrina (Saffron City, Psychic-type): Bite everything. Watch out for strong Psychics, but consistent healing should carry you through. Beware of Destiny Bond. If you have Surf by this point, overwrite Bite with it - STAB boosts the 95 BP Surf above the 60 BP Bite, even with super-effective status taken into consideration, and both are Special moves in this generation. Blastoise isn't really fast enough to have the flinch chance be a factor.
Gym #7 - Blaine (Cinnabar Island, Fire-type): Free EXP!
Gym #8 - Giovanni (Viridian City, Ground-type): More free EXP!
Rival (Route 22, pre-Elite Four): Zzz... Wait, are we in an actual battle now? Pidgeot, Rhyhorn, and Arcanine are as easy as usual, but Alakazam actually poses a threat these days. Beware of STAB Psychic. Take it down quickly - Strength or Return can hit its lack of physical bulk hard. Gyarados isn't going to do anything major unless it accidentally helps you by setting up Rain Dance. Venusaur, on the other hand, still has Razor Leaf. AVOID.
Elite Four Lorelei (Indigo Plateau, Ice-type): Blastoise resists Water and Ice moves, crippling Lorelei's main STABs. If you have Brick Break, you can probably plow through her Pokémon without much difficulty. Jynx is an exception, but it has nothing super-effective against Blastoise - treat it as you would any other Psychic. You can try using a strong physical attack on it, as Jynx’s physical defense is garbage.
Elite Four Bruno (Indigo Plateau, Fighting-type): The two Onix are not worth writing about. Hitmonlee and Hitmonchan are much like the Dojo back in Saffron - just avoid using physical attacks against Hitmonchan, lest it uses Counter. Kill Machamp quickly before it can set up with Bulk Up - alas, Blastoise has no super-effective attacks against it, so you'll have to make do with a solid STAB offense.
Elite Four Agatha (Indigo Plateau, Poison-type): Earthquake (or Dig) + any strong move (against the Ghosts, which have Levitate) should take care of her Ghosts and Poisons. Just remember to use Poké Flute if you get put to sleep.
Elite Four Lance (Indigo Plateau, Dragon-type): Beware Gyarados's Hyper Beam - you have no good counters for the beast. Fortunately, Blastoise's Defense makes you sure to survive it if you're at a decent level, giving you a free healing turn. After that, Ice Beam through everything that moves. Lance's team has no super-effective moves against Blastoise, but be careful around Hyper Beam and STAB Outrage.
Champion Rival (Indigo Plateau): Pidgeot is, as always, nothing to worry about. Alakazam, as a Psychic sweeper, is dangerous - use Surf or a physical move and pray for the best. Rhydon and Arcanine are easy if you still have Surf PP - beware of Extremespeed if Blastoise is at low health, however. Gyarados has Thrash again, so be very careful. Meanwhile, your old nemesis, Venusaur, has...Sunny Day + Solarbeam? Hm. If you have Rain Dance, save all 5 PP for this battle and then Rain Dance after every Sunny Day use. It halves SolarBeam's power and turns it back into a two-turn move. While that's still painful, you should be able to cause Rain Dance to be the final weather condition, leaving Venusaur with a two-turn 60 BP move and only Growth and (rainy) Synthesis as reinforcements. This only persists for five turns, but you can throw any remaining Ice Beam PP and neutral moves at it. It's risky, but POSSIBLE to kill the beast with this strategy. Using something else (especially if it has Rain Dance) is advisable, however.
Squirtle starts off with Tackle and Tail Whip. Tackle should be kept for a while, as it gives you an option to cover opponents that resist Squirtle’s Water-type STAB moves. Bubble comes at level 7, and it’ll be your only STAB option until level 13, which is when you get the much better Water Gun, which has twice the power. In between, at level 10, you’ll get Withdraw, which is kind of useless, since Squirtle’s Defense is high enough already. There’s no sense in delaying Squirtle’s evolution, as Wartortle only gets Bite a level later than Squirtle, at level 19, as opposed to Squirtle’s level 18. Bite is a very good move that provides nice coverage. Since Bite has the same power as STAB Water Gun, it’s best to use Bite when you’re faster because of the flinch chance. Of course, take weaknesses and resistances into account. At level 25, you’ll get Rapid Spin, which really doesn’t help at all in-game, though it’s vital on the competitive scene. You’ll get Protect at level 31, which really isn’t necessary unless you want to go for an extra turn of Leftovers healing. After evolving at level 36, Blastoise gets Rain Dance at level 42. It can be helpful, but you’re probably better off using that moveslot for a coverage move. Skull Bash comes at level 55, and is a pretty horrendous move, especially in the later stages of the game. Hydro Pump at level 68 gives awesome power, but its miss chance and the fact that it comes so late makes it not ideal, especially for nuzlockers who constantly get screwed over by miss-hax.
Blastoise has a wide array of TM, HM, and Move Tutor options. Because it has so many options, we’ll just go over the important ones. Water Pulse can be gotten relatively early in the game, after you beat Misty, and can serve as a replacement for Water Gun, as it is more powerful and has a nice added effect. However, it isn’t necessary to do so, especially if you have another Pokémon that would benefit more from the coverage that Water Pulse provides. Toxic, Substitute, Protect, and Focus Punch are all available, but there’s not much point in using them since Blastoise is more of a tank than a staller. Ice Beam, which can be gotten from the Celadon Game Corner for 4000 coins (or 80,000 Pokédollars) is a vital addition to Blastoise’s moveset. If you can’t afford it, go grab the Amulet Coin and grind for a while using the Vs. Seeker. You’ll have enough money in no time. If you’re too lazy to do that, or if you want more power, then Blizzard is always an option. Keep in mind that it has awful accuracy, though. Earthquake and Dig both provide nice coverage, though Earthquake can generally see better use on something else. Dig is a purchasable TM, though, so you can use it on Blastoise without worry. Brick Break also provides good coverage and is purchasable as well. Mega Punch and Mega Kick, as well as Strength and Double-Edge, may seem appealing, but Normal-type moves don’t really provide any extra coverage. Finally, Hydro Cannon can be used if you want more power, but it’s normally easier to just stick to Surf.
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.
Squirtle Line Ratings
What Nature do I want? Attack-boosting natures aren't the best, as Blastoise works off Special Attack. Do not use Careful, Impish, Jolly, and Adamant, as Blastoise needs all the Special Attack it can get. Speed-lowering natures don't really hurt, since no one uses Blastoise for speed anyway. Quiet, Rash, and Mild are all quite nice, though Modest diminishes the potential to use a mixed set.
At what point in the game should I be evolved? All the Geodudes in Mt. Moon give you Exp. to grind to Wartortle if you don't reach it from the Trainers alone, and you should have Blastoise by the time you reach Fuchsia.
How good is the Squirtle line in a Nuzlocke? The Squirtle line, like most starters, is awesome in a Nuzlocke. It has excellent coverage, few weaknesses, and solid defenses. Its bulk and movepool (including Fighting, Water, Ice, and Ground moves) will serve you well against many of Kanto's strongest Trainers.