Tabitha/Matt (Mt. Chimney): Fighting STAB takes care of all of Matt's Pokemon, while Tabitha's Numel can be handled with Rock Tomb.
Maxie/Archie (Mt. Chimney): Sharpedo and Mightyena are easily handled, although their abilities are a hinderance. Golbat can only be handled if Rock Tomb is in play. Camerupt as well.
Gym #4 - Flannery (Lavaridge Town, Fire-type): The Slugmas should go down with relative ease, so feel free to use Machop here. However, you should be careful with the Torkoal, since it has really high defense. Instead, you should probably use a special based Pokemon against it.
Gym #5 - Norman (Petalburg City, Normal-type): Machoke/Machamp is great against Norman. It wrecks everything, but do be wary that the final Slaking has Focus Punch. Using Bulk Up allows you to have even more certainty that things will just die. Let the mayhem commence.
Courtney/Shelly (Weather Institute): Machoke/Machamp handles either with care.
Rival (Route 119): Machoke/Machamp neutrally hits everyone here well, and Shroomish can even set off Guts. Combusken however, will be a bit of trouble with Peck.
Gym #6 - Winona (Fortree City, Flying-type): This is where Machoke/Machamp will most likely see a two-gym absence. The type advantage is not in your favor, especially since most if not all of her 'Mons outspeed Machamp, and they are all packing Aerial Ace. If for some reason you do want to try to take her on with Machamp, then your best bet would probably be Rock Tomb. I still don't advise it though. Use something else if you can.
Rival (Lilycove City): Same as before, but Swellow should be an avoid without Rock Tomb.
Tabitha/Matt (Lilycove Hideout): Machoke/Machamp should know how to handle Camerupt, Sharpedo, and Mightyena by this point.
Gym #7 - Tate and Liza (Mossdeep City, Psychic-type): This one is another gym Machamp should stay away from. Both the Solrock and Lunatone have Psychic, and despite Solrock not having the best SpAtk, they both have STAB. This is especially inadvisable since it is a double battle and they could both potentially target Machamp with Psychic. In addition, Machamp doesn't really have a good answer, with neutral STAB being the most effective attack it would have. Just like with Winona, use something else if you can.
Courtney/Shelly (Seafloor Cavern): Machoke/Machamp should know how to handle Camerupt, Sharpedo, and Mightyena by this point.
Maxie/Archie (Seafloor Cavern): Sharpedo, Mightyena, and Camerupt are standard. Remember that Intimidate is a chore to deal with, unless Swagger brings it back up. Crobat is more difficult to handle, meaning Machoke/Machamp should avoid.
Groudon (Cave of Origin, Ruby only): Machoke/Machamp should fight with Guts activated, only.
Kyogre (Cave of Origin, Sapphire only): Machoke/Machamp should fight with Guts activated, only.
Gym #8 - Wallace (Sootopolis City, Water-type): Machamp can set up on Luvdisc to take everyone else out.
Wally (Victory Road): Altaria, Delcatty, Magneton, and Roselia are easily handled. Gardevoir, not so much.
Elite Four Sidney (Ever Grande City, Dark-type): Yes, Foresight on Sableye.
Elite Four Phoebe (Ever Grande City, Ghost-type): This one might be a bit more tricky, but Will-O-Wisp helps Machoke/Machamp if it has Guts. Foresight is the best way as before.
Elite Four Glacia (Ever Grande City, Ice-type): They go down to Fighting STAB easily, but watch Machoke/Machamp's health.
Elite Four Drake (Ever Grande City, Dragon-type): Against Shelgon, Machoke/Machamp has the best opportunity to set up with Bulk Up. Otherwise, everyone can be handled with care. Although, Salamence and one of the Flygon have a super-effective Flying STAB move.
Champion Steven (Ever Grande City, Steel-type): Skarmory is not a good matchup, though Bulk Up solves Machoke/Machamp's weak spots. Otherwise, Claydol is a stalling match. Aggron goes down easily to STAB. The same with Cradily. Armaldo and Metagross are a bit tricky, as they have Aerial Ace and Psychic.
Post-Game: Not much in RS to do, really. But, Machamp handles well against Pokemon that can't 1-2HKO it.
Tabitha (Mt. Chimney):
Maxie (Mt. Chimney):
Gym #4 - Flannery (Lavaridge Town, Fire-type):
Gym #5 - Norman (Petalburg City, Normal-type):
Shelly (Weather Institute):
Rival (Route 119):
Gym #6 - Winona (Fortree City, Flying-type):
Rival (Lilycove City):
Tabitha (Jagged Pass Hideout):
Maxie (Jagged Pass Hideout):
Matt (Lilycove Hideout):
Gym #7 - Tate and Liza (Mossdeep City, Psychic-type):
Maxie and Tabitha (Mossdeep Space Center, tag battle with Steven):
Machop starts with Low Kick, Leer, Focus Energy, and Karate Chop unless it is Lv. 19 or higher, at which point it gets Seismic Toss instead of Low Kick. Karate Chop will probably be your STAB of choice for a good while. Seismic Toss is too situational to use, and is mediocre in the early game. Low Kick can be useful against some opponents early on, but late game is where it'll see a lot of use. At level 22, it gets Foresight. It is very handy against Ghost types, especially against Sableye later on. Level 25 gives you Revenge, which can actually be of good use due to the Machop family's low speed. Vital Throw is next at level 33 (level 31 if you forgo evolution for a little while. Also note that Machamp learns moves at the same level as Machoke). Vital throw is decreased priority and deals less damage than Revenge most of the time, but note that it cannot miss. You should probably skip Submission at level 41, due to its higher risk and relatively low reward. Instead, you might want to go for Cross Chop at 46. This will probably be your endgame STAB along with Low Kick unless you prefer the more accurate Brick Break, since it has 80% accuracy. Scary Face is learned at 51, but it probably isn't worth a move slot, since Machamp prefers to beat up Pokemon with raw power. Finally, Machamp gets DynamicPunch at 59, which would be awesome...if it could hit (If only No Guard existed in Gen III).
So to round out Machoke/Machamp's extremely type-limited level-up movepool, we now teach it some nifty TMs. Early in the game, Rock Tomb hits Flying Pokemon hard, and is a good option to help Machoke/Machamp gain some speed by slowing the target. Although, Machoke/Machamp will generally want to run better moves leaving no room for it. Also, Rock Tomb is in its pre-buff stage this gen. Dig can be alright as well, but isn't particularly spectacular. Earthquake is generally better. Strength is a good Normal move for Machamp and also disguises as utility, but it would much prefer Facade or Return to work with. Bulk Up helps it set up well, allowing it to tank physical hits and hit back very hard. Brick Break is notable, if Cross Chop is too unreliable.
Recommended moveset: Cross Chop / Brick Break, Low Kick / Earthquake / Foresight, Return / Facade, Bulk Up
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.
Machop Line Ratings
What Nature do I want?: Anything that raises Attack is ideal, such as Adamant or Brave.
At what point in the game should I be evolved?: You should be a Machoke by the time you fight Norman.
How good is the Machop line in a Nuzlocke?: Machop is a solid choice for an early Pokemon that can still hold its own against most oponents up to the late game, thanks to its high attack and decent bulk. However, it cannot be expected to fight everything, nor does it have good options outside of its STAB.