If you have a Machoke out (evolved from a machop) and you have no machamp, 
and if he gets down to 20 HP, he cannot attack without killing himself (He 
has karate chop which does 50 minus, and if you have 30 or less damage it 
doesn't work. Submission does sixty but he does 20 to himself, that's why 
he's so bad). If you de-evolve him, you have a machop who can do low kick (20 
damage) and has 50 hp.