If Link, Young Link & Toon Link can be in Hyrule Warriors, they can be in Super Smash Bros., and considering
SSB has Marth, Lucina and Roy, they could easily bring back Young Link, keep his
Melee moves (which Toon & Link have branched slightly away from) including the Fire Arrows and then give him some new aspects (like how Roy barely, if at all, feels anything like Marth anymore) and a new / altered Final Smash (could even be weak and give him a Fierce Deity FS that's just a transformation with sword beams).