Maybe I should just say the story I get from the images?
Tuma, the champion, and his servant, the dude in his colours riding the dino, run the Colosseum. There are six tribes around it, who compete annually in the Colosseum. They've each got a Glatorian to compete this season, with their own attendant, I.E. the small sets. They each battle in a series of fights, with their own agendas and personalities, and using their different attendants to scurry around the colosseum for a side-story. These guys uncover some sort of plot which brings the rugged gladiators togetether against Tuma. Tuma unleashes Dino-rider on the Glatorian, who defeat it by learning the value of Teamwork. Then they defeat Tuma together. Tuma reveals another plot-point, and then the Glatorian set out on an adventure that leads into the second-half's sets.
Or something.