Yuxa's name is presumably based off of the Turkish legendary creature, which is a 100-year-old snake with a dragon's head. This could be a reference to 100 years ago when Gibeon's Zygarde was in Rakua and that it is a 100+ year old snake itself.
https://en.wikipedia.org/wiki/Yuxa
https://en.wikipedia.org/wiki/Yuxa
Comments
Yuha is the exact romanized spelling and it has also been brought up that his name could be a reference to Yupa from Nausicaä.
Yuxa: https://www.pocketmonsters.net/characters/view/5155