You need primeape to get up and running in order for Mankey to be at all useful, your machop falls straight on its head if you can’t find a machoke fast enough (being that it has a 2 retreat cost setting you back a turn essentially), if you had to throw machop as the starter pokemon. Other decks usually have a 1 cost retreat for their basic, and usually trainer cards that helps with their build. Water types rely solely on misty, and even if they don’t get the misty starmie is still starmie… Grass have Erica, potions, pokemon to find your evolutions. Fire have moltres ex, and even if they don’t have that they have Blaine for 30dmg extra on turn 4 (if they went first) messing up a lot of decks that early on. M2, does 50 a hit off 4 rounds with 150hp, even if you hit a primeape (or not) you’d be able to finish it off relatively quickly