The "File Listings" I list here are just what sample number PSound picked up the sound as.
This is a rather surprising find, as these may either be unused samples (Why would the english actors have done the voices if they were unused?) or secret moves no one has unlocked yet.
After a talk on Planet Megaman (rest in piece, ye unstable site)...
1. The Shoryuken & Senpuukyaku can be used if you get the K-Knuckle. They use the same moves as the Hyouryushou and Rasetsuzan. Layer also has the same cries.
2. X's shoryuken is accessable when you get the Ultimate Armor.
However, the Hadouken remains a complete mystery...