It may sound dull to others, but I'd love the BOTW Champions to be added to the game. Specifically for Revali.
The reason being that my boy - absolutely - loves - Revali. On his first day at reception last year, I had to "fly" him to school, doing Revali's Gale and then paragliding him along. He would crouch down and say "Revali's Gale is ready to go ... ... ... Daddy now" and I'd have to pick up him, whoosh and then gently glide him to the floor.
He sleeps with a Link & Bokoblin, but in place of Revali, he as some sort of Ikea Eagle, which is also a substitute in his frequent games of "Captain Bokoblin":
BOTW is absolutely his life. He can recognise most pieces of music from the game within about 15 seconds of it playing.
But apart from playing BOTW, he loves playing Smash. And having his all time favourite champion available to him would be awesome. Plus he would have his alternate favourites of "Daruka", "Verbosa" and "Meepha" in there too.
If anything, it may actually spur Nintendo into doing a plushie range and we can quietly retire the strange Ikea eagle.