I can't stand Iris. I hate how they rebooted not only Pikachu at the begging of Best Wishes but also Ash by bringing in this girl who keeps calling him a kid. In the Battle Frontier and Diamond and Pearl arcs they establish that Ash is a well known and respected trainer. Granted Unova is a great distance away but the fact is he has a great deal of experience under his belt. She just irritates me. I'll be glad when she's gone.
I try to use at least one Pokemon that is new to me each time I play through a game.