Now here's where the problem is... You can't have Homing Attack AND shields at the same time. Homing attack (and jump dash) overrides shield abilities. Therefore, Classic can't use the fire shield's boost, the thunder shield's double jump, or the bubble shield's bounce. If I were to take out the homing attack to allow these shield abilities to work, gameplay would be MUCH much more difficult, believe me.
There IS a way I could possibly have both, though... Either we (okay fine I) find out what in Generations' code controls looking for the "A" button to be pressed while in midair for the homing attack, and I remap that to the "X" button, then we can have proper X-button homing for Classic Sonic. OR, I could do the same, but for the shield abilities, so the shield abilities would end up being jump + X instead of jump + jump.
I mean, whatever works, right? :/