I have heard them in on YouTube and I would like MP3s of these songs such as "Eight Melodies" and "Ballad of the wind Fish."

I have found that some people have links up but they don't work :(

As someone who was closely related with bringing you the Smash Bros. Brawl Soundtrack, I tell you:

THE LOST TRACKS ARE NOT EXISTING

They simply are a project of someone, who collected several game tunes or remixes of them, packing them together and uploading them.

It's more of several people linking to a bunch of remixes for substitutes. Unfortunately, I'm the one who linked the ballad of the wind fish remix, but forgot to credit the person who made it so yeah it ended up in there without an artist.

http://shachinobu.zukyun.jp/mus/game/zelyume/rk-kaze.mp3

Link directly from the artist's website. Check it out, their stuff is orgasmic.