Alright, starting on Wolf and DK now.
Wolf:
The biggest problem that I have is how to get around his five or so different approaches.
Any sort of landing lag or something and you eat a face full of Blaster. His FAir comes out fast, his BAir has good range, FSmash punishes landing lag, Shine interrupts everything, etc.
I know we have that UThrow CG, up to 30% something.
Wolf's ability to kill is a bit below average, so don't be surprised if you survive a fresh DSmash at 110% (DI that up).
I really don't know what neutral is bad for him. I used to think FD, but he has an easier time punishing our landing lag there.
I have also been toying with using Double Team vs. his Blaster a bit. I think its a pretty good mixup that'll work well against this particular character.
Lylat and Frigate are nice though.
Donkey Kong:
DK loves his BAir as much as Marth loves his FAir. If misspaced above, you should be able to pop under him and use a FAir without getting hit.
Don't be obvious with DAir above him because of his long arms reach. You will likely eat a DSmash, USmash, UTilt, or a BAir.
While in the air be careful if you are still in hitstun and you wanna try to hit him with your DAir. Some of the time DK can just use his UAir and hit you without him getting hit at all.
Don't forget to DI DSmash to the side, it shouldn't kill you even at 110% on Neutrals.
If you manage to footstool him while offstage... that pretty much equates death for him, so keep that in mind.
Watch out for his DTilt to Down B traps.
Pressuring his shield, so that you can easily shieldpoke works wonders too.