Juggernaut/Gladiator info:
Gladiator's powers are based on his confidence. He already has superstrength, speed, durability, flight, heat vision, etc. The more confident he is the stronger he becomes, but I don't know if that applies to all of his other powers. Strength-wise, he's at the top of the Marvel chain IIRC.
Juggernaut, however, is at least on par with him, but he's written really inconsistently. His strength level can increase depending on how he's using the gem of Cytorrak (since he's not very intelligent, this hampers his potential). I used to read comics some when I was a kid, and I remember Thor remarking how his strength had increased "a hundred-fold". He also became so strong he was punching holes through reality/breaking open gateways to new dimensions or something silly like that (I think that version was called "Trion" or "8th Day" Juggernaut).
That's not the normal level for him, though. On average, he's generally Hulk/Thor level strength-wise. Potentially, who knows...and btw, the cartoon isn't the best way to go by the comics. They followed them pretty closely, but they aren't canon in the X-mythos so some characterizations tend to be a little off.