What dual types you would like to see in the future?

For me I have some soft spot for some dual type

Electric/Fighting (Hopefully as a special attacker this time around)

Dragon/Fairy (I don't mind Mega Altaria, it has a cute hat. I just think it would be neat to see a Dragon/Fairy Pokémon that isn't a temporary form.)

Water/Steel (Empoleon is currently the only one with said type combination, that being said in the Spaceworld demo 97 of Pokémon Gold and Silver, there's two evolution whose name are Ikari and Gurotesu that was intended to be Water/Steel. I still love Empoleon's animations in Pokkén Tournament tho!)

As for those that are not introduced yet.

I would personally love to see either an Ice/Poison, Rock/Ghost or Fairy/Ground Pokémon. The potential of a Fairy/Ground Pokémon sound quite huge, 2 immunities with 4 resistances, I can see this being really powerful.