Some feedback
Medium Kick Pushback should be increased. It's currently shorter than the light kick and the crouching light or medium kicks.
Heavy Kick seems like it'd be better as a special.
Medium and Heavy Punch have no push-back. As least with the Medium Punch there's enough time between blows to block...
Matter of fact, Crouching Heavy has no push-back either.
I'd recommend changing the hitboxes on the Raging Blast, since it currently can hit a downed opponent.
I'd shorten the "Noooooooooooooooooooooooooooooooooooooooooooooo" that is his KO cry.
And now for some possible special intros.
vs. Ginyu: "You can still choose to admit you're wrong and leave this place. Alright, one or the other, lets settle this right now."
vs. Frieza: " I am the hope of the universe! Ally to good! Nightmare to you!"
vs. Cell: "There's no way you can beat me with your stolen fighting techniques. Now, give up."
vs. Fat Buu: "This is a Super Saiyan."
vs. Super Saiyan Vegeta: "Alright Vegeta, let's settle this."
Some other ideas (for later)
Bring in the Kamehameha. (EDIT: Just saw the above post)
Solar Flare could work as a stunning move to set up for a Raging Blast or Kamehameha.
Kaio-ken, I'm not so sure about. After becoming a Super Saiyan, Goku never used the Kaio-ken again, at least in the manga. He did in DBZ, but that was exclusive to filler. It's your call, I suppose.
Perhaps instead of the Spirit bomb toss, he does what he did at the end of the Android 13 movie, where he ends up absorbing the Spirit Bomb's power and defeats Super Android 13 with just his aura.