Ok, I just started to play this game, but Im already really far. This game is really challenging. And yes, you visit a lot of the same places as in colosseum, but it is way different. The fact that you can now purify several pokemon at the same time is very appealing, but at a cost. To quickly purify a pokemon in the purifier, you need to have several other pokemon handy. But dont worry, as a new twist in the game, you can catch wild pokemon. Honestly, if you really want a shadow pokemon to be purified, it is much faster to train it in battle, then take it back to agate village to purify it at the stone.