Now that we have had one mount for each ludus so far, I keep thinking and wondering if we some day will get a second set of mounts and riders for the ludi. I hope so.
Some ideas:
Ludus Magnus - The third horseman. We already have two horses, I wouldn't mind a third. Apparently there was a historical gladiator type called the Andabata that were on horseback and had helmets that didn't let them see out. Might be interesting to work with that somehow.
Morituri - Not sure, but there are plenty of interesting options, especially if they are mythed up. The Nile would give us crocodiles or hippos. From the desert maybe a camel. Smoke if you got em.
Legio XIII - I've said it before, but a giant wolf or a bear would make so much sense to me as a mount for one of these guys. Northern forests. Make it happen. Or something mythological. A baby dragon.
Zephyri - A wolf or bear would work here too, for a Norse mount rather than an Atlantean mount. Or how about an elk? Maybe Wendigo is elk-like enough already. We could throw a saddle on the Wendigo.
And I suppose the big question is about the Hellenics. Possible Pegasus? Who knows?