i think if metal sonic was in the only difference is that he has a variation of a final smash and that his down b is an infinite version of zelda's neutral b but can move around slightly.
All of his A moves would be the same, but his B moves would all be different.
His neutral B would be that diamond shield thing from SA2.
His up B would be chaos control. (So he could do a sort of short-range warp)
His side B would be the electric dash from Sonic CD.
His down B would be the slower electric charge also from Sonic CD.
And his final smash should be a slower version of Sonic's but he can fire projectiles.