I should teach someone Return... but who? Mewtwo just learned Psystrike, and I may replace Flamethrower with something else, as once I get to raising more Fire types, him having Flamethrower will be redundant.
Is Return a decent move for battle? I'm considering teaching it to Runaway. I'd like to round out my Psychic types with a multi-type moveset.
Once you have full friendship on a Pokemon it's base power becomes 102, so yeah it can be really powerful. Frustration is the opposite as you have to have the Pokemon absolutely hate you but that's hard to do and really the result is the same.