Unlock Fighters
Hold the R button over certain fighters to unlock:
Ryu unlocks Zero
Chun Li unlocks Demitai
Dhalsim unlocks Dan
Bison unlocks V. Ken
Vega unlocks Shin Akuma
Kyo unlocks Geese
Terry unlocks Mars People
Ryo unlocks Goenitz
Kim unlocks B. Iori
Katsumi unlocks E. Mr. Katate
Two Hidden Bosses
Simply beat 35 fighters in survival to unlock Athena and beat 36 Fighters to unlock Red Arremer. Then hold the R button over Tessa to use Red Arremer and hold the R button over Genjyuro to use Athena.