https://docs.google.com/spreadsheets/d/1e7fRsX8Pp5EyyUoXTT9iODI23jvwAqJDd08J7XHpv3M/htmlview?sle=true#

Couple of interesting things to notice here.  First of all, those who were excited at the idea of 36 Street Fighter tracks are going to want to temper your expectations.  The Vega and Guile themes on the website are the only ones that are actually new arrangements.  All the others are the Type A and Type B themes for every character from Super Street Fighter 2, taken straight from the original game.

On the other hand, Mega Man got a shitload of new remixes.  There's more new Mega Man songs in Ultimate than the total amount of Mega Man music in Sm4sh.  More new remixes than Castlevania got, too.

Not very many new Splatoon remixes, but those games' soundtracks are good enough that they can get away with just the originals.  I'm really glad Ebb & Flow in particular made it in.

Snake's codecs from Brawl are all back in.



No word yet on whether or not they ended up recording new ones for characters that weren't in Brawl.

Also, it turns out Cloud is in World of Light after all.

They're reused from Brawl, so nothing for the newcomers since then.

The most prominent omission people have noticed is that Porky Minch is nowhere to be found in the game.  His boss fight from Brawl doesn't return, and there's no spirit for him either.  It's strange that he isn't represented at all given his prominent appearance in Brawl, and then the trophy he got in Sm4sh.  Plus, Porky is one of the two main antagonists from the Mother series which makes it odd that they wouldn't include a spirit for him, especially when much more obscure Earthbound characters like Buzz-Buzz and Ness' Dad are there.

The other character in the same boat is Sylux;  All of the other hunters from Metroid Prime Hunters are present as spirits except for him.  Plus, Dark Samus has alt colors that reference all of the other hunters except Sylux as well.  There's also the fact that he's rumored to be the main antagonist for Metroid Prime 4, too.

This probably wouldn't mean anything at all if it weren't for the fact that they've found spirits for every generic Mario series enemy except for Piranha Plant.  The current theory is that characters that are being withheld from Spirits mode might be on Nintendo's short list for potential future DLC fighters.