I'd guess one of three options:
1: requires five Jawas vs a full Droid team with extreme difficulty requiring gearing of a (currently) practically useless faction.
2: requires five Imperial Troopers vs a full Ewok team with C3P0 since he'll likely have synergy with them also with extreme difficulty. Imperial Troopers are a heavily used and very powerful faction so it would probably be so difficult that it'd make using Troopers on the mythic Ewok Assault Battle look easy.
3: requires five Ewoks. This would basically just be a move by CG to force users into gearing Ewoks. Outside of the Yoda Legendary it's always been the opposing faction that is needed to unlock the character so this one really wouldn't make much sense.