Otto hidden options:
Mono-Ground (HUUUUUGE  SAND POTENTIAL):
Steelix-M/Dugtrio-A/Excadrill/Seismitoad/Gastrodon/Swampert-M/Wishcash/Quagsire/Rhyperior/Golem

Mono-Psychic:
Slowbro-M/Slowking/Bronzong/Jirachi/Metagross/Starmie/Bruxish

Mono-Fairy:(MASSIVE TRICK ROOM POTENTIAL)
Mawile-M/Magearna/Klefki/Azumarill/Primarina/Tapu Fini/Diancie(M)/Carbink

Mono-Ice: (hail potential)
Sandslash-A/Aurorus/Walrein/Dewgong/Lapras/Cloyster

Mono-Bug: (sticky webs spam)
Shuckle/Crustle/Durant/Scizor-M/Armaldo/Forretress/Escavalier/Wormadam/Araquanid/Golisopod