What you might call dual type moves are actually more like Psyshock; they use their actual type to calculate same-type attack bonus, and a different type to calculated weakess and resistance. For example, a Water-type will get STAB on Scald, but it will only be super-effective on things weak to Fire moves.
Water super effective against Grass? Broken af. Fake
Dual type attacks making the metagame even more complex. I am here for it competitively, and intrigued by it in-game wise. Maybe a gym leder who specializes in dual-type attacks, idk.
WaiT, I just realised that the XY announcement was almost 6 months ago and that we'll probably get another game announcement (Aqua Sapphire & Magma Ruby ) in another 6 months