Unlike most peoipel, rather than going through the main storyline with a full team or six, I usually focus on a team of 2-4 Pokmeon and the rest are HM slaves, so that way they can be at higher levels than if you focus on evenly training six.
My Pearl "Team" and their jobs:
Dodaitos the Torterra, LV.100: Physical Sweeper
Dootakun the Bronzong, LV.100: Tank
Fuwaraido the Drifblim, Lv.100: Special Sweeper
The rest are HM slaves.