I had a similar idea to this poster too, mind if I share a possible move list?
~Young Link~
B: Bow- Similar to YL's from Melee
Side B: Deku Nut- YL throws a Deku Nut at the opponent which acts like a mini smoke ball, blurring the area around them for a moment or two.
Up B: Spin Attack-YL does his spin attack upwards.
Down B: Mask Change- Young Link takes out the Deku Mask and places it on his face. This move has a bit of lag and you can still be struck by attacks/smashed away.
Mask Change pattern: Young Link-Deku Link-Goron Link-Zora Link-Young Link
~Deku Link~
B: Bubble Spit- DL spits a bubble at an enemy, this can be charged, but like Diddy's popguns, if charged too long, the bubble will burst.
Side B: Dash Attack- DL spins towards the opponent like his attack in MM.
Up B: Flower Booster- DL produces two flowers that send him into the air, he then slowly drifts down.
~Goron Link~
B: Goron Punch- A heavy punch is sent rocketing towards the enemy. This attack has a small wind up.
Side B: Goron Roll- Goron Link rolls towards the foe, as he rolls, he picks up speed and becomes harder to control. After rolling for a while, spikes jut out of him, causing more damage to enemies.
Up B: Goron Pound- GL leaps into the air, tucks into a ball and ground pounds. This can be used as a recovery move but due to the fact that Goron Link is so heavy, his recovery is quite poor.
~Zora Link~
B: Barrier- Zora Link creates his electric barrier around himself; electrifying any enemies who try and strike him. This lasts for a short period of time and after the barrier fades, Zora Link must recovery briefly.
Side B: Zora Boomerang- Zora Link fires his boomerang like fins. This attack strikes twice.
Up B: Dolphin Leap- Zora Link leaps straight into the air, his arms at his side. This has good recovery possibilities but very little offensive capabilities.
Final Smash: Fierce Diety Link: Young Link places the Fierce Diety mask on himself and briefly transforms into the all powerful warrior.
Taunt: Young Link removes the mask he's currently wearing (Like Kirby; getting rid of his powers) and gasps slightly at the shock of taking it off (like the transformation scenes in MM).
Sorry for such a long post ^^ I just had a very similar idea to this posters!