Sorry to reply to such an old post, but I didn't want to start a new one, if there's already an existing thread.
I came up with the idea of Young Zelda as a character by myself only today. Finding it intriguing, I tried searching for a thread and found this.
I already saw that there are some people who don't like the idea at all. But Zelda fans, like me, might actually like the idea, especially those that liked Young Link in Melee.
I thought that Young Zelda might actually share a few attacks/items that Link used in his games, after all, Adult Zelda also uses his magical spells in Melee. But Young Zelda doesn't necessarily have to be a clone.
Let's take a look at Zelda from Wind Waker, the first game where Zelda actively helps in a battle. Sure, her only attack are the Light Arrows, but there are several items Link can use that might fit to her personality.
Up B: With the Deku Leaf, she can gently hover through the air and knock everyone back who comes to close to her.
Neutral B: Zelda puts up the Magic Barrier and protects herself against all kinds of projectiles, thrown items and explosions. The barrier can only last for a short time.
Side B: Zelda charges the Light Arrows. If charged completely, they detonate in an explosion of light when hitting the opponent.
Down B: Well... either it's another item/attack I can't think of yet, or she can do a similar thing to Adult Zelda and transform into... Tetra!
No idea for attacks for Tetra yet, but as you can see, it's actually possible to make a Young Zelda without making her a clone. And I always preferred Zelda's younger version, and now I am hoping that she might one day be playable on Smash Bros.