New abilities:
Anti-Magic
Grants immunity to Psychic AND Fairy type moves. You can use Magic Eye to get around it. Give it to a fighting type for maximum laughs, but anything that could conceivably have a "Field of Reality" or extreme magical resistance could have it.
Equalize
This pokemon's attacks hit for normal damage and ignore immunities and resistance. They can never hit for supereffective damage, however. This one belongs to some kind of champion of justice, one that treats everything equally. maybe make it Cobalion or Virizion's hidden ability, so they can hit stuff that resists them since a lot of stuff resists grass and steel.
Moves:
Fairy Might
Fairy, 80 BP, 100% accuracy no additional effect. I want a weaker but more accurate alternative to Play Rough.
Luna Flare
Fire, 120 BP, 90% accuracy, special. Hits either the opponent's physical OR special defense, whichever is lower. Also supereffective against ghosts, since I like to think fire hurts dead stuff. Make this the signature move of a box legend.
Chilling Touch
Ghost, Physical, 120 BP, 90% accuracy. 20% chance to paralyze the target. If the target is already paralyzed, 20% chance to cause a flinch. Supereffective on fire types because it's cold. There, give this to the other Box legend. Now they murder the shit out of each other and have really REALLY annoying moves.
Cross Counter
Fighting, status. If the user is hit with a fighting, the move is cancelled and immediately used by the pokemon that just used Cross Counter. Give it to Throh and Machamp, since one uses a deensive fighting style, and the other can counter easy since it has 4 arms.
Shield Bash
Steel, physical, 70 BP. Uses defense instead of attack when calculating damage. Learned by Shieldon, Bastiodon, and Aegislash. Puts Aegislash in shield form when used.
Powder Cloud
Poison, special, 60 BP, 90% accuracy. Always poisons the foes if it hits. Many poison types learn it, notably Roselia, since Roserade needs to make use of Technician.