Theres a class of Gladiator called the Rudiarius, who are gladiators who won their freedom but still want to fight in the arena. Since their free they dont have to use the costumes their masters please, soo, they will have a vast set of items to choose from, you can choose stuff to make it look like an hoplite, but a hoplite class, sorry no xD
Besides hoplites in the arena would result in massacre, hoplites need a well armed formation to atack properly