Seeing as Terrak beats/heavily weakens chomp and lando perhaps something like power up punch in the 4th slot would be better to clean, and there are heaps of other cool options that could work well supporting terrak like baton pass, healing wish, or toxic.
Lopunny-Mega @ Lopunnite
Ability: Limber
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Fake Out
- High Jump Kick
- Return
- Ice Punch
Mega Lopunny is a cool mon to pair with CB Terrakion because they share similar checks which Terrakion does an insanely good job at pressuring and chipping away at, putting them in range of Lop's moves for when it cleans late game.