For example...Freeze Shock. An Ice move that had the potential to paralyze. What if it gained Electric has a second type, due to this? Now all of a sudden, you have a move that's completely walled by every single ground-type imaginable, and the move that was once considered super-effective now no longer has any effect whatsoever on the type that it's supposed to be super effective against.
And Scald. Would it have Water/Fire because of it's chance to burn? It's such a useful move in competitive play, but can Fire-types freely switch into scald without any fear of it causing super-effective damage? Would Heatran freely switch into Scald and get a free flash fire boost?
The point being from all of this is...if dual-type moves were to exist (and assuming that the aforementioned moves get an additional typing), it would make things unnecessarily complicated, and why? Why is there a necessity for dual-type moves, I don't see anything wrong with our moves being single-typed in any way, so why is it needed? Especially if future dual-type moves get introduced, what's going to happen then? It'll just be a mess of dual-type moves that aren't needed in the first place, nor do I think are they going to be needed anytime in the future. .___.;;
You didn't really read what I said. What you said only accounts for number 2 on my list of possibilities.
What I'm talking about in possibility number 1 is that if you have a Water/Electric dual type move, if a dual type attack means combining the effect of each type into one turn (rather than two seperate turns)....
So a Water/Electric type attack would hit a Ground type pokemon super effectively because of the Water part of the attack rather than the Electric part.
For all we know a dual type attack could just be two attacks of different types occurring in the same turn. So first up you have the water damage...and then the electric damage follows. Like using doubleslap where each individual slap is a different type.
We don't know how dual types will work right now. So at this point it's just a guessing game.