Bankai - Kaiouken
Hollow Form - Super Saiyan (What with it taking over and what not)
Hollow Form Bankai - Super Saiyan 2
Now with that said, Ichigo needs to go somewhere and read a book in Hollow Form so that hell be like Goku and Gohan in the Cell Games, forever in Hollow Form. Isnt that place where Urahara trained him comparable to the Hyperbolic Time Chamber?