I was thinking of doing a varietion of the monotype challenge with using 2 types.
I'm thinking 3 one type and 3 of the other.
I still need access to surf and fly.
You don't need to give me teams, just two types that goes well with each other.
Okay so as I've said in the comments, I think Steel and Water would be good for a dual-type challenge, simply because they get useful secondary types, excellent defences and good coverage moves. They can also somewhat remedy each other's weaknesses. The following Pokémon are useful for either their secondary types, their coverage, or their utility.