I was thinking about ALBW, and after some thought I came to the realization that Ravio would actually make a really unique fighter if it implemented ALBW's item rental mechanic.
Perhaps items such as the different elemental rods could be implemented as Ravio's specials (Ex: Tornado Rod as recovery) but in order to use them he would need Rupees to get the items first. He can do so by beating up enemies and knocking Rupees out of them ala Coin Battle, and once he has a set number of Rupees (displayed on his HUD like Little Mac's Power meter) he can purchase an item from Sheerow who drops it off. So if Fire Rod is neutral B yet I don't have it, I tap neutral B when I have enough Rupees and Sheerow will fly it to me. Considering there may be multiple Ravios in battle, just make the Rupees a specific Ravio can earn the same color as that character. So default Ravio could only pick up purple Rupees, green Ravio can collect only green, etc.
He keeps the special items as long as he isn't KO'd, but once he is, Sheerow takes them. (but not his overall number of Rupees) I imagined that for his normals he could fight using a bag of Rupees that he lugs around on his back, in which the less Rupees he has the lighter he will be making him more mobile yet weak, but when he has a lot of Rupees he is heavier which makes his attacks stronger at the expense of hurting his mobility.
Sadly though, I don't expect a new character from the Zelda series and even then I think Ravio would be too recent for consideration in this game.