Burst loved its anime-only tournament, so if X wanted to do one I think the optimal time would be with Burn's debut. They could change it from Burn distributing Phoenix Feather and letting word of mouth carry his plan, to specifically setting up a tournament featuring Phoenix Feather to show it off on a grand scale.
This would be a good way to get everyone that isn't Team Persona another fight as well. I imagine the bracket would be somewhat like this:
A quick explanation of each round:
Multi has acted as Bird's main guide for the Pro Scene, so giving him a final lesson (Shu and Lain-esque, just with less hatred) where she pushes him to start evolving as a person and a blader would be cool. You could say it's too early, but even though we're like, 8 chapters in, I think everyone already agrees Bird needs to step it up at this point.
Maiden and Kadovar are both adult pros, so a match between them would be cool. Also, they know each other, so a little backstory into what the pro scene was like around 10 years ago would be cool.
Ekusu sweeps Toguro obviously, but Toguro's whole thing is not having confidence in himself. So Ekusu beating him, but still affirming his strength (in a "stand proud, you're strong" type of way) would be nice.
Tbh I don't have much of a reason for King to fight Chop Pan specifically, but getting to see the dynamic between Team Zooganic would be nice.
Maiden takes up the classic shonen "sensei" role despite not actually battling much, so having her face off with her Team again would be cool. Also, some more insight into Multi's family would be cool, and I'd assume, if anyone, someone like them would have it.
Ekusu vs King would just be a classic rematch episode. King only lost because he switched to playing defensively, so seeing a full-on clash between the two with no holds barred would be great. They did say King of Beasts with weaker than X Dash 4X, but we've already seen different applications with X Dash, like with Burning Maneuver. So seeing King experiment with that would be great.
As for the finale, we'd finally get to see a fight between Ekusu and Maiden, since originally Ekusu got to skip fighting her since he's already a pro. And of course, once Ekusu wins his prize is the chance to fight Burn, Battle Island style, where he will then reveal his Phoenix Wing.