I think Cerro Altman is the strongest among Cerro, Oubu and G&D except for the protagonist's aura.

I usually like to watch Altman. I've seen many different ultramen. Among the three, I think Ciro is the strongest, because Ciro has inherited the ability of Saiwen, with many skills, a weapon dart and strong fighting ability. He studied under Leo Altman and learned the famous stunt of Leo-flying Leo, and his fighting skills were excellent.

So I don't think the other two Altmen can beat him.