The final incarnation of green is a tough one, I'd highly recommend using the homing stars (double homing) weapon to defeat him and the mobile character. In the first phase he will seem to block all your attacks but there is a simple trick to this. If you jump up or down a level he will follow and while he is jumping between them you can hit him, thus simply jump up and down (just hanging down and swinging up is better) and he will do the same leaving you taking no damage and easily finishing this phase.
In the second phase he will be much more aggressive, actively attacking you, throwing you when close. Just keep your distance and much as possible, using the two levels to jump up and down to avoid him as needs be. With the homing stars there is no need to aim, just avoid his attacks. Care should be given to his star throwing attack, these are easy to avoid but when they bounce off the walls and fall to the lower level they can still hit you so stay clear of the walls.