Due to the beginning of the song, a rainy stage would best suit this song. The energy is medium-high; not so high where it'll get your blood pumping to the max, but just high enough to have a good fight.

If you're a fan of Monstercat and/or Muzzy, check this song out. It's from the album Colours & Distractions.

Looped pretty well, may need a bit of work later.

This song has good pacing throughout, remaining energetic enough to fight to. The song's steady beat is good for a sort of technological stage.

A remix of Zero Virus Stage 2 from Megaman X5 and Invisible Full Moon from TouHou 8. If you've ever heard both songs, you've probably noticed a similarity in them, and this remix brings both into harmony.

Looped pretty well.

If you like vocaloid music and Hatsune Miku, here's a fast-paced song that's good to fit a mostly serious stage (I say mostly because of Miku's voice). The loop is a bit weird, but it works.

Opening song of the anime Fairy Tail. Good, steady beat, sort of light. Would work on a sunny stage, where the setting isn't so deep/dark.

This is a rough sketch of the Town theme from the game Etrian Odyssey Untold: The Millennium Girl. It comes on a music disc with the game if you buy a physical copy.

I figured this could fit on the menu screen, if anything. Though it may not be energetic like you'd expect a brawl to be, perhaps you're looking for something more relaxing to listen to while you browsing through Brawl's menu screens.

This song is from the video titled, "The Last Cat on Earth" by Jimmy Wong. The loop is a bit rough.

Get out Alive by Three Days Grace.
Looped pretty well.

Metal version of the final boss fight with Bowser in Yoshi's Island, and first track in the album BadAss: Boss Themes - Volume II released recently on OCRemix.

Second battle theme of Etrian Odyssey IV. I think this also works better as a main menu theme rather than an in-game battle theme, but that's just my opinion.

This is a J-Core mix of the opening theme from the anime Tsukihime, A Sacred Ancestor. I'm not new to looping, but I haven't looped much, so I can't say it's perfect. You be the judge.

I looped this song before I realized it was already on Brawl Vault, but this one loops differently. I cut off around 40 (maybe?) seconds off of the end, but I think it loops nicely.

This is a mix of B.O.B. by Outkast and Flowering Night by ZUN (and Haru?) As far as TouHou goes, I don't know much, but I think this sounds great. I think the loop is good, too.