Don't get me wrong, I'm not saying that Noivern is trash without DDE, it's still playable. But there's no way it's going to be a 'no fun allowed' level card without it. You lose both your one attachment lock capability and your two attachment attack.
That i agree with, it's not Toad-Lock, or anywhere near it. One thing about Noivern is that you may never get his second attack/GX attack off because of the energy difference.
If I was gonna break it down in depth here's what you're looking at:
Double Dragon Energy allows you to play Darkrai/Noivern. Probably an 8/4 Energy split. You set up Noivern and attach a DDE and just go ham with item lock. After a few turns, you have enough energy to go ham with Darkrai EX. You can use Alter of the Moone for retreat costs. Overall, I think the deck would me pretty good. But Post rotation, we lose DDE, so now you have to change 8/4 to 10-12 Dark. EXP Share stays at four, attaching to Noivern mostly. You are better off going first, deck puts you behind a lot going second. Overall, I think Noivern/Darkrai COULD do well, but it's going to be sketchy post rotation.
Now you could do Noivern/Umbreon, but we lose the weakness trio.
Then there's the Drampa GX version of Noivern GX. 4 Dark 4 DCE 4 Rainbow? Allows you to get his second/GX attacks off, but you lack early damage.
Noivern/Zoroark may get clunky if you want to use the BREAK.
Noivern/Garb? Don't ask me how this one works, I just have 6 Dark/6 Psychic in my head. Item lock early then clean up with Garb? I'm spit balling at this point.