First my secondary character:
Alt mode: organic Phoenix
She carries no weapons and the only real ability she has is a universal translation program.
Bio: A mechanic by trade, she met Maximus by chance one day while she was visiting Kaon. (The Predacon capital city) While most predacons are bitter and jaded to Maximals for the way they treat them, Maximus had only emerged from the Well of Allsparks just a few days ago, and so hadn't developed any of those biases. The two became fast friends, and the two have spent much time together. Exploring the unknown and going on many adventures. She cares for Maximus greatly, admiring his innocence and curiosity.
As for Axis' personality herself, she's very strong minded and gets frustrated when she's underestimated. She's also very protective of her friends. Maximus especially.
Stage-name: Speed Demon
(I'll give credit when I find it)
Weapons: Built in plasma blasters in his wrists.
Bio: The self proclaimed "Fastest thing on wheels", Hotshot loves nothing more than racing at top speeds across long open roads. Which is why he absolutely despises being locked up in the arena. He's been calling for some kind of revolution since day one, but without ever having much of a plan, his movements never gain traction.
Altmode: Cybertronian mobile artillery platform
Weapons: Bombs, missiles, rockets, grenades, and otherwise more explosives than you could ever hope to shake a stick at. His fingers can also act as machine guns.
Bio: He joined the decepticons towards the start of the war, but not by choice. He followed orders loyally but never actually cared much for the cause itself. He's surprisingly happy to be in the arena. Yeah the constant fighting isn't ideal, but it's a thousand times more preferable to the war, and he finds the calm predictable lifestyle pleasant.
Stage-name: The Flying Devil
Altmode: Cybertronian helicopter
Weapons: One arm mounted gatling gun on each forearm. Otherwise he prefers to fight up close and personal.
Bio: Cyclonus ("I hate it when they mistake me for that other guy") is absolutely psychotic. A cackling madman who loves the thrill of battle. He was partners with Demolishor during the war, and the two became good friends. Despite one being calm and peaceful and the other being insane and bloodthirsty, they get along surprisingly well. Needless to say he loves being in the arena, and fully intends to stay.