I've always like to think about which pokemon, each gym leader and E4 member liked the most. It tends to be the highest level one, but some gym leaders (the Kanto ones) tend to have a new higher level pokemon each game. Lets put the most likely favorite with each Gym leader, E4 member, and champion. Correct it if needed. I'll start with Brock, since onyx is most likely and I don't think he would actually evolve it into a Steelix.