Well Zelda is highly on watch to get changed. It isn't hush hush or anything as it's been put onto public places.
Other things that stand out are Mario's fireballs being able to be put out in an almost obscene quantity, Link's boomerang being one of the other projectiles to compete and being a hit confirm for any move he wants, GnW bacon not being that useful, Ivy's UpB seeming to hit everything everywhere and extremely easy to pull off + KO power galore, and... Olimar's doodad on his head should change colors to indicate the current active pikmin, also his fsmash serves little purpose for how long it takes, dsmash is almost always better. OH! And Dr Mario's pills are good against all of Olimar's pikmin, unlike regular Mario and his fireballs.
There will be other stuff I'm sure, I can also smell possible Mewtwo nerfs in the future because he has moves so good they could be a standalone character.
In tier related news my buddy played Olimar in Brawl and loved him and just recently had the time to put work into him for PM and I have to say he's pretty decent. I vastly underrated how good up air, up smash and fair are. The purple pikmin puts out Fox upsmash level strength on a safe disjoint, pretty janky stuff.
I'm not even concerned with space animals, do you people think they are THAT real at the moment? I feel as though the tech does exist to overthrow them somewhat, and with characters AND stages to counterpick we can do a lot more than just Marth on FD. Falco is a much lesser issue. It's just like... We all saw Armada use Pit against Fox on several stages and he can chain grab, arrow hit-confirm into fair and just carry him off the stage. The scary part is that it isn't even crazy tech-heavy stuff, he wasn't waveshining him off the stage, it was just basic movement, reading DI here and there and playing solid. I can't even imagine how Fox would get nerfed in a way that doesn't completely destroy him or leave him in his seemingly dominant state still. Weakening Upsmash to KO 10% later would be fine, but he is still the same character and will continue to do the same things. Like... Upsmash is incredibly strong, and he can combo into it, but there are other moves in the game that have CRAZY KB and can be comboed into. Captain Falcon's knee, Sheik's fair, Mario can almost do any move into haymaker, Zelda's kick, Marth's dair, Ivy's UpB which can be landed after any of her many launchers. I'm perfectly fine waiting this version out and developing and dealing with this silly moves, but the uncertainty of whether or not this game will be updated tomorrow... or 5 months from now puts me on edge. I know a lot of the stuff the PMBR does should remain secret, but the community deserves to at least know what to expect, are there going to be major changes, are they working on bugs, people speak of a new server for online is it true, should we just accept the current version and play it as is for a few months? Regardless, this version is very solid and I very much enjoy this game.