Actually, you've got a few more to bag after Evice. If you've snagged all the Pokemon so far, you'll still need to get two more of the Johto starters, Shuckle, Togetic, Smeargle, and Ursaring, and you'll need to capture and purify all 48 Shadow Pokemon before you get Ho-oh.
If you've missed some, you can find some of them again at the same locations as you fought them the first time around, and if they are not there, they are either moved to the Deep Colosseum, Pokemon Lab, and Team Snagem's Hideout.