I'd like to bring Serebii's Pokearth
to your attention. Particularly the fact that it lists all the trainers and their teams, as well as their improved teams for the ones that level up in rematches.
I'd like to help but I seriously doubt I can contribute much since everyone else is already on top of things. One thing I'd like to mention though is that PI Carlos's Goldeens all evolve, so he ends up with three Seakings. Sadly, that's in D/P. He only has one Goldeen/Seaking in Platinum.
And Gahagan, it only doesn't work at Lv100. Any other level it does work.