In the final battle of the movie they go past tengen toppa gurren lagann and form super tengen toppa gurren lagann. The old one is the size of it's face.
Even stronger is the anti spirals super grand zamboa. When super tengen dose a comic giga drill breaker the anti spiral super grand zomboa dose a giga drill breaker too. They clash and super tengen, tengen toppa,, chougina, and ark gurren lagann are beaten but with a last ditch try from gurren lagann simon kicks logic out and not only stops the drill that at this point is most likely the biggest thing in the universe but also controlled by the strongest beings. Then breaks through the anti spirals super grand zomboa giga drill breaker and then launches himself with the help of lagann at the anti spiral and fist fights him.
Either simon or super tengen has to be the most powerful. They beat a foe that could do things god could only dream of. O.o