For Dark Metal in EX TRR, does it provide both at same time but only 1 of it? Or will you choose it? This is important as there are some cards that say "discard all metal enegys attached to [Pokemon name]
No, you have to. It's rather confusing, but you would lose your DM energy on say, Charizard d. Just think of it, for attack effects, providing everything (but only being one) and for energy costs, providing one. I dunno how to explain it >_>
Dark Metal Energy is just like Rainbow and anything else that is multiple types at once.
You don't get to choose, ever. No choices. If it provides Dark and Metal, then it's Dark and Metal.
If an attack says discard all Metal, anything attached that provides Metal Energy gets discarded. If an Energy card is providing multiple types and an attack says discard all Energy of a certain type, all those Energy cards that are providing that type at the time of the attack must be discarded.
With Charizard DS, I don't know what its attack does. If you had L/M/M/DME attached and the attack says discard 1 Metal, you could discard either of the actual Metal Energy or the Dark Metal Energy, since the DME is providing Metal. If the attack says discard all Metal, you would have to discard the DME as well as the two Metal because those Energy cards are providing Metal Energy.
So, DM Energy is just like rainbow, however it provides just Dark and Metal, only 1 at a time, while Rainbow provides all, P, G, L what have you, only 1 at a time. OK, I know. Salamance DS is a "Discard 1" thingy, while I think charizard MC is a "Discard all" thingy.
Bingo. You could combine it with Dragonite DS, but it only puts them on your Bench and discarding four will give you 110 damage with Metagross DS's Crush and Burn. Way to go Charizard DS, you're dumb.