I'll have to reply to this topic stage-by-stage. I choose the most basic tracks, because I want to keep the same songs as in the original games, with a few exceptions.
301. Delfino Plaza: "Delfino Plaza"
302. Mario Circuit: "Mario Circuit"
303. Rumble Falls: "Battle for Storm Hill" - the only track from Jungle Beat in the game.
304. Bridge of Eldin: "Twilight Princess Theme"
305. Norfair: "Norfair"
306. Frigate Orpheon: "Metroid Prime Main Theme"
307. Yoshi's Island (BRL): "Yoshi's Island"
308. Halberd: "Revenge of Meta-Knight"
309. Lylat Cruise: "Star Fox 64 Theme" - I should choose the Star Fox 1 theme but I like this one better, and it's about as basic.
310. Pokemon Stadium 2: "Pokemon Main Theme"
311. Port Town Aero Dive: "Mute City" - This is where things get REALLY ugly. Instead of Car Select and Mach Rider, why couldn't they have put in "Like a Snake" from GX? To me, that would be a no-brainer.
312. New Pork City: "You Call This A Utopia?" - Also known as "Isn't It a Utopia", this song played in New Pork in Mother 3. Luckily, I eventually found out.
313. Castle Siege: "Fire Emblem Theme" - Am I the only one here who thinks the opera suits this stage very well?
314. Wario Ware, Inc: "Wario Ware, Inc."
315. Distant Planet: "Environmental Noises" - I bet you'll want to sue me for this, but because the Pikmin Main Theme had too small of a music loop, I chose the ambience. Perhaps I should've gone with Forest of Hope here.
316. Smashville: "Animal Crossing Theme" - When I hone my skills against computer players here, I fight the three StarFox characters, due to their collective nickname "Space Animals".
317. Mushroomy Kingdom: "Ground Theme" and "Underground Theme"
318. Summit: "Ice Climber" - This stage is the closest we'll ever come to Melee's would-be IceTop level. That's why I call this level "IceTop Summit".
319. Skyworld: "Skyworld" - Is this track a combination of overworld and skyworld? I've never played Kid Icarus.
320. PictoChat: "PictoChat" - I honestly believe this is the only good track for that stage. I also fight the Kirby characters as I hone my skills here because it reminds me of Canvas Curse.
321. Shadow Moses Island: "Cavern" - There's no Metal Gear Solid Main Theme, so I chose this because it suits the cold winter night.
322. Battlefield: "Battlefield"/"Battlefield Version 2"/"Melee Main Theme" -I just threw in the Melee Main Theme because it was the first update on Smash Bros Dojo and I kind of imagined it as the theme for this level at first. This is the only stage with three basic themes. I also fight Zelda, Kirby, and Capt. Falcon here because of the alloys.
323. Final Destination: "Final Destination"
324. 75m: "Donkey Kong" - The only really good track for this level.
325. Luigi's Mansion: "Luigi's Mansion Theme" - Can you get anymore suitable than this? Add in the fact that it's the main theme for Luigi's Mansion...
326. Mario Bros.: "Mario Bros."
327. Spear Pillar: "Dialga/Palkia Battle at Spear Pillar"
328. Hanenbow: N/A - I fight Pikachu, Lucario, and the Trainer here.
329. Flat Zone 2: "Flat Zone 2"
330. Green Hill Zone: "Green Hill Zone" - Why oh why didn't they remix this? It was all about the 3D sonic games with the music, when the 2D games were so much better.
331. Pirate Ship: "The Great Sea" - That's what everyone thought the level would be called before Brawl was released. They should've included the track used on Tetra's Ship in The Wind Waker instead of Village of the Blue Maiden restored.