I'm looking for a certain type of sheet music, but I'm not sure how

[Taser9090]

I imported an awesome game called Daigasso! Band Bros. P, and it's a Nintendo game that's sort of like Guitar Hero/Rock Band. The main difference is that the song list is all instrumental and all user-made.

I'm not into J-Pop, so I want to transcribe American pop songs into the game. Though, I'm not sure where to look. I'd need sheet music that contains all parts of the original song.
So far, I transcribed American Author's Best Day of My Life because I used Finale NotePad to convert a MIDI into sheet music. There are no other friendly MIDI files that Finale can open.

Anyway, I guess what I'm asking is, where can I get sheet music for popular songs that have all the instrument parts? Is there a term for that (searching "band sheet music" just leads me to high school bands)?
Is there a program that can recognize MIDI files and outputs a better sheet than Finale or MuseScore?

[JDMEK5]

I use my first notation program, "Notation Composer" for MIDIs. It not only usually does ok, but if it does turn into a big mess, there's a neat tool that shows exactly where each note attacks. If it's not exactly the same as written. But I'm really happy with it. And I believe there's a free 'reader' version too. Idk how well that would work though.

As a semisolid free option there's also synthesia, but that can get real messy if you have too many instruments going at once.