Banette Crest: This pokemon uses its attack stat when using special moves. Grants oblivious (ability). Attacks used by this pokemon cannot be resisted and instead deal super effective damage to those who would resist it.
Oblivious prevents taunts (trick room) and intimidate from activating.
Examples: Gunk shot hits steel types for x2 damage. Klefki takes x4 damage. Ghost moves deal super effective damage to normal types and dark types. Sucker punch deals x4 damage to fighting/dark pokemon (this may be a bit too much)
Edit: Felt like what I suggested was too weak so I tweaked it a bit.