you need a different camera for every champion. you also need variables for each camera and unit, and an integer variable to store the currently selected unit's number. whenever you press right, the integer increases, and camera[integer] is applied. also, a special effect is created above the head of unit[integer]. whenever you press left, the integer decreases, and the whole stuff is repeated. quite an easy task - it turns a bit more complicated when you don't want any mirror matches, though. this system enables me to create as many champions as I like, and the only thing I have to do is set the variables at map initialization - I don't have to bother editing the trigger, because everything else is automatic.
hope that helped