Disagree:
-Mr. Game and Watch: I don't think he's as horrible as some say, but I guess I just adjusted to him. Yes, I think he's weaker, but not enough to the point of uselessness.
-Martha: again, he's not that horrible. He's weaker, but his nerf wasn't as impacting as Mr. Game and Watch's, who is still tolerable. He's pretty high in EventHubs' constantly changing tier list. Lucina, on the other hand, ranks quite lower currently for some reason.
Agree:
-Olimar: I do feel he's worse now. I never learned how to play as him correctly in Brawl, but I remember he was effective.
-King Dedede: I don't recall him being so bad in Brawl, and given that Bowser is better now, I question why would anyone use the former instead of the latter. I miss his silly final smash dance, same for Luigi's.
-Falco: I guess as an attempt to de-clone him further, he's quite worse than Fox now. Same question from above applied here.
-Meta Knight: well, not a surprise as some say.
As for Zelda, yeah, she lost her best move, her down special in Brawl. Neither agree nor disagree with the nerfs, I never got to play well as her in either game.