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Caps will probably appear randomly as you buy soda pops, will be kinda common when you search in the box-island thing, some wild pokemon will have them, find them using stoutland, buy them in the plaza thing, buy them in the battle facility, a rare pickup find, I don't think they will be that rare, maybe gold ones but you won't need that many if you breed.
As for levels I'm led to believe that the training island and plaza will be effortless ways to train pokemon without using them, and as far as the people who played an hour of the games seems like you can rematch trainers after a while without a vs seeker or something.