I guess the easiest way would be to get and complete a Wonder Mail for that Pokemon. However, this doesn't happen often, so it's best to just recruit them by defeating them in dungeons. Also, in order to recruit a pokemon, either the regular way or from Wonder Mail, you have to have its Friend Area.
Only you and your partner evolve at the end of the game.
i am not sure about if they are the leader but they can be a partner
nope
You will never know because ther are always different questions, but you can chosse pikachu as your partner if you do not become pikachu.
beat Raquela's.
You have to turn them into the leader (You!) first.
walk into Pokemon square. if bellsprout says a Pokemon is coming a Pokemon will come and faint.and since your a rescue team you and your partner handle it. then for that rescue you get a clear feather. then sit back and watch the magic
You have to beat the game.
i dont think you can get cyndaquil, only as a partner i think.
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You cant, that's part of the effect of substitute.
you have to beat the whole game the go to the friend area and the faster way is if you beat the whole game and push B then pick your partner and take him of the team