Sonic Heroes is considered an iconic song that even shows up in random Sonic games where it has no business appearing. It's cheesy, but catchy.
I dislike that they removed the original version or the original remix for stuff if they made a new remix. Except for the times when they didn't.
Great Sea, Yoshi's Island, and even Jungle Japes died for new remixes, while Gerudo Valley, Star Wolf (despite the character not even appearing!), Dark World and a couple others get all the remixes they want, along with including the originals.
For reference, of the 5 Zelda stages in Smash 4 Wii U, 4 of them have a version of Dark World on them. And yet we can't have two versions of the Great Sea, even if the original was better. Nor can we have three Yoshi's Island remixes (of the same song) because of reasons. Jungle Hijinx can have 8 different versions of the same song, except for one version of the song (that's fully orchestrated btw). I mean, you're including 8 versions already... why not throw in the one with the highest sound quality...
There were also some pretty strange song cuts
- Gritzy Desert. Was inexplicably cut for who knows what reason, despite working just fine on basically any Mario or Yoshi stage. For the first time ever, Smash got a bunch of Mario RPG music, and yet the first Mario RPG song to ever appear in Smash was cut...
- Underground from Mushroomy Kingdom appears on the 3DS, yet isn't anywhere on the Wii U. They couldn't even throw it onto Mario Maker or Peach's Castle for some reason.
- Fountain of Dreams was held back for the clearly planned ahead of time Dreamland (it's obvious based on a number of factors), and that's kind of sneaky.
- Humoresque of a Little Dog is in all three Mother games, and yet was cut. It works perfectly on Onett, Onett is the first place the majority of people first heard the song. I realize there's some licensing junk with Mother music... but seriously.
- I would have rather had the DK Rap cut entirely than what ended up happening, The lyrics to the song are far too iconic to be messed with like that. And low and behold some other songs didn't have to deal with arbitrary time restrictions (Fountain of Dreams is still in its 3+ minute glory).
- Yoshi Story 64 is on Yoshi's Island Melee, a stage that's entirely unrelated and it doesn't really work well. I would have rather had the Mario 3 Medley on Yoshi's Island, Mushroomy Kingdom doesn't necessarily need it, and it works better on YI:M.
- Nintendo whips off Delfino Plaza remixes for minor one off hidden stages in Mario 64 DS, but can't make any Mario Sunshine remix at all for the game that literally has the most iconic location in the game as a full level (and a decently popular level at that) and its main villain as a new comer.
- Mario Maker's song list is downright silly. It actually had 5 songs, standard for a DLC stage, without drowning the stage in filler music from games that never even appear in Mario Maker.
- There shouldn't have been any music that appeared on the 3DS, but not the Wii U. This includes the GB Dreamland medley, Lumiose City, and Underground. I think those are the only three, so it's not like they'd be breaking the file size by making sure Smash 4 Wii U has all the music of Smash 4.
- There are far too many remixes for stuff that already had remixes. Dark World, Jungle Hijinx, the Legend of Zelda main theme and the Mario ground theme did not need any new remixes at all. Brawl pulled some fairly obscure songs to remix, and this game seems to play it really safe with the songs they chose to remix.