UPDATED 9/03/11
Gokaiger changes they haven't done, as of ep 29 and the movie (they become Battle Fever J)
Changeman
Kakuranger-Red Ninja and Yellow Ninja (Yellow became Black in ep3; Don, Ahim and Joe became Black, White and Blue in ep21)
The following were not done yet when this post was made but now has been done:
Liveman (Don became Green Sai in 12, Marvelous became Red Falcon in 25, Joe became Blue Dolphin in 25 and Luka as Yellow Lion in 25.) The whole team in Ep 30.
Gokaiger changes they haven't done, as of ep 29 and the movie (they become Battle Fever J)
Changeman
Kakuranger-Red Ninja and Yellow Ninja (Yellow became Black in ep3; Don, Ahim and Joe became Black, White and Blue in ep21)
The following were not done yet when this post was made but now has been done:
Liveman (Don became Green Sai in 12, Marvelous became Red Falcon in 25, Joe became Blue Dolphin in 25 and Luka as Yellow Lion in 25.) The whole team in Ep 30.
Bioman (Don transformed into Green in Ep 19 and the whole team in 28)
Flashman (Don transformed into Green in Ep 19 and Ahim became Pink in Ep 12, whole team in 27)
Maskman (Yellow in ep 12, whole team in 28)
Marvelous became Abared in 25 And Don becomes AbareBlack in Episode 29.
And Gai has yet to become GaoSilver, MagiShine, Go-On Gold and Go-On Silver (even though he became Go-On Wings in 19). He has become AbareKiller (Episode 29) and DekaBreak (Episode 26).
http://www.super-sentai.net/go-kai/super-sentai.html