I had an idea that could make it so Zelda and Sheik wouldn't have to have their own character slots, while still giving them an extra special.
Alright, call me crazy, but I think it's about time we got a fighting style for Zelda and Sheik that would truly make them "Zelda/Sheik", while still being effective as individual characters.
The key to this is to make the transformation a lot faster, I mean faster than Melee, and make it able to do a small amount of damage to whoever is around. That way, one using this fighting style could learn to utilize combos from from both characters, and do such things as starting a combo as Sheik and finishing that combo as Zelda or vice versa. Or if Zelda has a better recovery move, you could quickly switch to Zelda and use it.
Of course we'd then have to think, would transform still be a down special? Or could we move it to a different button, such as a taunt button? Moving it to a different button would certainly make it easier for people playing as each character individually by not accidentally hitting the transform combination.
You could add another special to Sheik such as changing her down special to a Deku Nut that stuns once it hits the ground. This of course was taken from the way she uses a Deku Nut to stun Link while she disappears in Ocarina of Time, which is also what her Teleport move was inspired by.
Now these are all just suggestions, open to comments and criticism or other ideas. I just want to make it so my main (Sheik) can have an even more unique fighting style that utilizes her transformation to Zelda.