This air battle thing has me thinking, what about all the Riders who don't have any sort of flying capability? Examples I can think of are Meteor, Ichigou, Kuuga, Nigou, Hibiki, Amazon, IXA, etc.
Also I'd love to see Kiva be able to take part in air battles because of Castle Doran or Den-O/Zeronos because of the Den/Zero Liner. I just think that would be something to see.
air battle doesn't always mean the character need to FLY, it might also mean you are now capable of aerial rave/combos, riders like amazon would probably gain double jump to capitalize on this, super 1 and V3 have dozens of aerial kick variations to cater to this too, let's not forget RIDER JUMP that the hoppers have and is a general "rider power" that most showa riders have, and i'm sure meteor will have some flashy aerial combos for him to show off
riders who doesn't excel in both are obviously given anti air attacks to counter the inability to fight on equal grounds, this might have a form of diagonal projectiles or an upward rider kick/punch as example