What Pokemon evolve by level?
Almost all of them. I recommend being more specific with which Pokemon you are wondering about.
You have to Level it up in Battles. Once you get to a certain level... It will evolve right after. Another way pokemon evolve is frienship, once there happiness level is high enough, and you level them up one more level they will evolve. The last way for Pokemon to evolve is with a stone. Few pokemon evolve from evolutionary stones, but when they do they evolve as soon as you use it on them.
It depends on the situation. If you raise a Pokemon in the Day Care and its level is too high, it won't evolve no matter what. If you pressed B during its evolution, it will try to evolve again after gaining another level. BUT !!! IF THE POKEMON IS A LVL TO HIGH FOR EVOULTION THEN YOU HAVE TO RAISE ITS LVL BY ONE BY FIGHTING OTHER POKEMON a Pokemon wont evolve when its in…