He uses quite a lot of Pokemon, which I wont be covering here for the sake of time. However, if you choose Grookey, his team will always have a Sobble, Drizzile, or Inteleon. His full list of Pokemon can be found here.
Usually, he sticks to his Rookidee and Dubwool at the beginning of the game, but then he goes crazy with his team. I think the route 7 battle is where he made the most changes.