There should a separate room or like a section so that you can use 1 character for training, then the battles will be short. (And it is not available during tournys)
That kind of defeats the point of it being a collectable card game then really, doesn't it? The idea is that it is not extreamly easy to level cards. If you want to level a certain card, then only play with an eight card deck, then you have a 50% chance of drawing that card to level.