I'm going to have several Pokemon this time as opposed to just six. That way, I have some back ups or I can change my team often as the game progresses instead of waiting until after I beat the game.
I'd like to use: Natu, Chikorita, Tododile, Cyndaquil, Houndour, Hoothoot, Mareep, Smoochum, Red Gyarados, Sudowoodo, Hypno, Rocky aka Onix, Espeon, Umbreon, Dratini, Krabby, Poliwhirl, Corsola, Sneasel, Pidgey, Ariados, Ledyba, etc.
I'm not going to use all of these Pokemon to battle Johto trainers. I'm going to level some of the pokemon up in the wild only. If they need their levels to drastically raise in order to battle the E4, I'll trade them to Platinum, and then trade them back.
Reason: I love the overworld sprites, and I might not want to do a new game.