Switched back to Platinum after playing about halfway through HG (at E4 right now).
Got the badge in Snowpoint, did all of the stuff with Galactic and Giratina, went to the electric gym and easily beat everyone there with Torterra and Swampert. Earthquake and Mud Bomb, respectively.
Now I'm using the VS Seeker on random trainers to prepare for Victory Road and the E4. Most of my team is in their low to mid 40s so I'm trying to get them all to level 48-50.
Platinum FC: 3268 7322 8943
HeartGold FC: 3698 1539 4947
White 2 FC: 3612 1944 2721
3DS FC: 1779-0800-2195
My friend safari: Noibat, Gabite, Druddigon