Whimsicott

This Whimsicott runs Life Orb instead of the usual Focus Sash or Fairy Feather, a break from the Charm and status-based Whimsicott most opponents expect. Prankster guarantees priority Tailwind even against faster leads. Moonblast and Grass Knot both get a damage boost from the item, and Grass Knot specifically is a tech that can obliterate a Mega Swampert that would otherwise wall the rest of the team. Modest with Special Attack and Speed investment keeps it outpacing non-max Garchomp on top of everything else.