Here's my extremely long list of songs I REALLY FREAKING WANT in Smash 4!
(In no particular order

1.
Series: Fire Emblem
Name: Rival Battle
Stage: Arena Ferox, Custom Stage
Reason: Need I say it? It SOUNDS like a fighting song. It is from important parts in the game, and... it sounds epic! Did I mention it sounds awesome?
2.
Series: Kid Icarus
Name: Medusa's Theme
Stage: Reset Bomb Forest, Custom Stage
Reason: K, did you click the video? No? Click it.
Click it yet? Cool. Now you know why I want it in.
3.
Series: Animal Crossing
Name: Town Hall or Mayor's Theme/Isabelle's Theme
Stage: Animal Crossing's stage, Custom Stage
Reason: One of the few Animal Crossing songs that can fit into Smash. Plus, it sounds SOOO cute and quirky
4.
Series: The Legend of Zelda
Name: Groose's Theme
Stage: Skyloft, Custom Stage
Reason: I dunno, it just fits in with the wacky, crazy item fest that Smash can be.
5.
Series: Pokemon
Name: Champion Battle/Red's Theme
Stage: Pokemon's stage, Custom stage
Reason: Extremely well received, popular, and could be Pokemon Trainer/Red's theme. Also, its awesome.
6.
Series: The Legend of Zelda
Name: Vs. Ganondorf (The Wind Waker)
Stage: Wind Waker's stage, Custom Stage
Reason: WHY OH WHY is there not a Ganondorf boss theme in Smash yet???
7.
Series: Metroid
Name: Super Metroid Theme
Stage:
Norfair 2.0 Metroid's stage, Custom Stage
Reason: You HAVE heard this song before, right?
8.
Series: Star Fox
Name: Star Fox 64 Opening Theme
Stage: Star Fox's stage, Custom stages
Reason: I love that DUN. DUN. DUN. DUN NUNUHNA! NUHNUHNAH NUHNUHNAH, NUHNANUHNANUHNA!
9.
Series: Kirby
Name: Gourmet Race
Stage: Kirby's stage, Custom Stage
Reason: Ok, I know that Gourmet Race is in Brawl, and I liked the heavy metal version. But please, gimme the real Gourmet Race. Please?
10.
Series: Dillon's Rolling Western
Name: Overworld/Final Boss
Stage: Depends, Dillon's Rolling Western may not get a stage.
Reason: My favorite track from Dillon's Rolling Western, and if Dillon gets the Isaac and Golden Sun treatment, he'll be an AT and have this as his series' song. No complaints here.
11.
Series: Mario Strikers
Name: Luigi's Theme
Stage: Mario Strikers stage, Luigi's Mansion stage, Mario Stage, custom stage
Reason: Between this, Dark Pit's theme, and Gerudo Valley, Smash 4 will officially be MEXICANIZED!
12.
Name: Bowser's Theme
Stage: MARIO GALAXY STAGE, SERIOUSLY!!!orbowserscastle
Reason: See; My Ganondorf (Wind Waker) Reasoning.
13.
Name: Solaris' Battle
Stage: Sonic stage, if any, custom stage
Reason: My top requested song Pre-Brawl. Sure, we got His World, but if it's gonna be instrumental, then just give us this MUCH more badass version.
14.
Name: Dark Samus' Theme
Stage: Metroid's stage, Custom Stage
Reason: You heard it, right?
15.
Name: Clock Town
Stage: Skyloft, Custom Stage
Reason: Admit it, Termina Field was a slap in the face for Majora's Mask fans. Clock Town pls.
16.
Name: Pilotwings: Hanglider Ver.
Stage: Pilotwing's mysterious stage that has yet to been shown (the layout)
Reason: Pilotwings has a song that sounds good for fighting to? YES!
17.
Name: Nintendo Land Plaza
Stage: Nintendo Land's inevitable stage
Reason: I dunno, same as Groose's theme :3
18.
Name: Grima's Theme
Stage: Fire Emblem's stage on Wii U
Reason: I'm not explaining this.
19.
Name: Dark Pit's Theme
Stage: Kid Icarus' stage on Wii U or Reset Bomb Forest
Reason: You know this needs to be in. Don't deny it. Gerudo Valley is lonely, after all.
20.
Name: Boss Battle
Stage: Reset Bomb Forest
Reason: HYPED! HYPED! I AM BEATING THE EVER LOVING CRAP OUT OF MARIO!!! HYYYYYPPPPEEE!!!!
-This song
What do you all think?

I may need to spoiler tag this...