Uhhh...to be a competitive battler, he would definitely have to get rid of pikachu.
Not really.. I've actually played around w/ using a Light Ball Pikachu.
Also this is based on his personality, and the pokemon he already has. He wouldn't toss aside Pikachu.
To be a competitive battler (a good one at least), he would have to use pokemon at his disposal that are the most effective...not the ones he is attached to.
Anyways, he could utilize Gliscor and Infernape. I would switch Infernape with Charizard and Gliscor with Pikachu (again i'm breaking the rules, but i really hate pikachu). Staraptor could be of some use as well, but I don't know who it would replace. His team would be pretty susceptible to ice though.