This website where you create an account, choose which sprite you want, then choose which beginer Pokemon you want. (You can also choose Pikachu and other none powerful Pokemon) Then you choose a map to explore (Their are 24 in total) and walk around and look for Pokemon. There are other trainers you can see on the map, and you can challenge their team. Either a live battle, where they control their team, or computer controlled, where a dumb computer controls the oponents team team.
You can also challenge the gym leaders or Teh 1337 4.