If I were to pick a new Zelda character I think I would go with Lana, Linkle, Tingle, Skull Kid, Ghost Zelda, Tetra, Vaati, Midna & Wolf Link, Ravio, Medli, one or two of the champions (preferably Mipha), Ruto, Impa, Agitha, Fi or Malon because that'd be a funny joke character.
Changes I would make to existing characters is...
Link: After doing his
he pulls out the paraglider. His shield can now reflect projectiles. He has costumes for Oot, TP and SS Link along with Gerudo disguise Link because why not? His Final Smash is one of the divine beast or a Guardian.
Zelda: She has a new
. Her
covers more distance.
Ganondorf: His
is an energy ball. His
is similar to Mario's where he uses his cape to reflect projectiles. His
is floating upwards. His
is a punch to the ground causing a shock-wave. His Final Smash is OoT Ganon and you control him like Giga Bowser. All his
attacks involve magic and swords.
Toon Link: Give him the deku leaf after his
. Give his down taunt a hitbox.
Young Link: His
has him become a Deku Scrub and shoot up using a deku flower. His
is becoming a Zora and shooting his boomerang fins. His
has him become a Goron and ground pound. His up taunt has him take out his ocarina and play a random song from OoT or MM. His side taunt is his taunt from Melee. His down taunt has him put on the Keaton mask. His Final Smash is the Great Deity. His costumes are the originals from Melee, HW Young Link, wearing the mask of truth, Dark Young Link and the Giant mask.