This is in-game.
Grimmsnarl @ Expert Belt Ability: Frisk - Drain Punch - False Surrender - Spirit Break - Ice Punch
Grimmsnarl @ Leftovers Ability: Prankster - Reflect - Light Screen - False Surrender - Spirit Break
Attacking is so much better in-game. Playthroughs are all about hyper offense, and a supportive role is generally weaker than all-out attacking. In competitive, support Grimmsnarl is much better due to Prankster and dual screens/Thunder Wave, but in-game, those are practically worthless. Grimmsnarl has a colourful offensive movepool, so there's no shortage of coverage options either.
Hope I helped!