Torchic should have gotten more experience as a Torchic before evolving and going beast mode as a Combusken. Like how Axew should have more battle experience before becoming a Fraxure, its so the evolution is more realistic and easier to swallow. Yeah, Pokemon do evolve when convenient for the plot, I don't really have a huge problem with it unless it's really really too much.(Roggenrola evoling with little battle experience against Clay's Excadrill.) Though Torchic had been with May for a long while anyway and likely got some training off-screen(There were scenes of it iirc.), Torchic did help with smaller things like helping out against Carvanah, weakening Wurmple, and hitting Team Rocket a few times so it didn't really matter much to me.