According to Cort, who has talked to Tetsuya, and who I am assuming is a reliable source

REAL:
Tetsuya (Fox) vs Ganon
Tetsuya (Fox) vs Ganon 2
Tetsuya (Fox) vs Ganon 3

Tetsuya (Purin) vs Yoshi
Tetsuya (Purin) vs Yoshi 2
Tetsuya (Purin) vs Yoshi 3

FAKE:
Everything else. Here are some of the ones I have.

Tetsuya (Mario) vs C. Falcon   <-- Cort says that this is fake, even though this is widely known as an awesome Tetsuya vid
Tetsuya (Sheik) vs Samus
Tetsuya Fox vs Fox
Tetsuya Fox vs Falco
Tetsuya Link vs Pikachu        <-- Does this one make anyone else laugh?