He is the lord of the demons that are unleashed upon the surface during the events of the game.
He can use teleporting sword combos (Hyrule Warriors + source material) and switch between heavy broadsword (Smash attacks) and light twin swords (Regular a moves, derives from source material). Those are new, copy-pasting Arcfire and other moves (Classic Link) isn't or is less new.
Jigglypuff was popular, got in SSB. Ghirahim is also popular, takes spotlight so Sakurai looks at him pretty early.