Some more abilities:
High Spirits: Raises Sp.Attack when suffering(in the same manner as guts)
Pokemon to have it: Togepi, Togetic, Togekiss, Cleffa, Clefairy, Clefable, Uxie, Mesprit, Azelf, Mew.
Smooth Rock: Raises Speed.
Pokemon to have it: Geodude, Graveller, Golem, Ryhorn, Rydon, Aerodactyl, Larvitar, Pupitar, Tyranitar, Nosepass, Regirock, Registeel, Cranidos, Rampardos, Rypherior, Probopass.
Underweight: Halves the Damage from Low Kick and Grass Knot.
Pokemon to have it: Gastly, Haunter, Gengar, Krabby, Kingler, Mew, Misdreavus, Celebi, Duskull, Dusclops, Dusknoir, Drifloon, Drifblim, Togepi, Togetic, Togekiss, Uxie, Mesprit, Azelf, Phoine, Manaphy.
Breakneck: Raises Speed and Attack each turn
Pokemon to have it: Aerodactyl, Pikachu, Raichu, Heracross, Yanma, Yanmega, Sneasel, Weavile, Gible, Gabite, Garchomp.