As an exercise, I'm attempting to derive deck designs for Zexal characters as they would be near the start of the XYZ era (assuming that card release order was mostly like our own). While Rio Kastle was a duelist before episode 1 of Zexal, if you look at her signature Ice Bird cards in comparison with what people were using at that time, one gets the impression that Rio's season 2 deck was a gift to celebrate coming out of her coma - full of cards that she'd missed the release of. So what would her old deck actually have looked like?
To build one up, I drew heavily from the filler cards she'd been given in video games. Cards like Mother Grizzly, Penguins, other water support, even Sirocco the Dawn. While it's not very clean, it would put up a fight against the generally low power level of the (pre-)Season 1 Zexal era. And because she's ended up with a wider variety of levels than her brother, she's able to fill her extra deck with more of the early XYZ monsters.
As part of the exercise, this deck uses no cards from later than Generation Force. But if anyone has any thoughts about other cards or strategies better suited to the era, or sees something else I missed, feel free to comment. Remember that Synchros are unavailable, as Zexal tries to pretend those don't exist.