So, I'm aware that generally a round of "games" could be sponsored by an emperor or noble but was there ever a gladiator sponsored by a particular patron or group and put forward as their champion?
Basically, beyond being the organiser of a whole Games, were there opportunities for sponsors to attach their name to proceedings?
Gladiatorial events were generally put on by a single troupe. Gladiators in a troupe (familia) were very close and would train and fight together. This process was very expensive.
A wealthy patron looking to increase/cement their status would pay a troupe to perform in a festival with a myriad of other events. For this reason, it would be against their interests to allow another financier to get a piece of their action.
There are some cases of patrons financing a single gladiator, this was rare due to the fairly large support structure. Some gladiators inevitably got famous and special fights were organized around this.
I should add that gladiators themselves did get sponsors, and you would see advertisements that used their image.