I remember someone making a suggestion earlier about some type of "de-evo" item, and it was heavily rejected. With that said I'm glad to see this has a lot of support because I've made my fair share of stupid mistakes. Evolved my pickup meowth before, my chansey, a mankey I made for metronome and just today I accidentally evolved a friends drowzee for metronome. I think the little cup implementation makes even more of a case for this, whether its some type of toggle or an in game item to de-evolve. I haven't started any little cup poke but after making several metronome comps it's definitely frustrating having to stop evolution so many times.