The team: https://pokepast.es/0079641ee6fc747e

General strategy:
- Kill 1st Pokemon with Metagross unless it's a faster Fire type (in which case switch to Latios and use Surf)
- Explode on second Pokemon unless it's an easy kill for Metagross, then switch to Heracross
- Use Heracross to defeat 3rd Pokemon (if Metagross is still in, use Explosion)

Anabel 1: Shadow Ball, Explosion, send in Heracross, Brick Break (if Meta dies, IB+IB Alakazam)
Anabel 2 (Heracross lead): BB+BB, switch to Metagross, SB+SB, Explosion

To consider:
- Slaking instead of Heracross (Adamant, @Choice Band, Hyper Beam/Return/EQ/Shadow Ball)