As far I recall, Asura is a star-buster. That's powerful and all but no where near powerful enough to beat TTGL.
Scaling can also mean bringing TTGL down to Asura's size (ie Planetary), which is prolly how big TTGL should've been anyway outside that whole distorted space dimension
It was the size of a galaxy.
You see that thing they were fighting on, and those two big disks the Anti-Spiral grabbed for his Big Bang Attack?
Yeah, those were galaxies. Super Galaxy Gurren Lagann also dwarfs planets as well and it's much weaker than TTGL.
Didn't Asura defeat the God of his universe? I don't think the scary robot is going to win here. Then again, I could be wrong.
The only thing Chakravartin made was the planet Asura lived on. Well, he claims to have made it. He also created Naraka, which is the afterlife of Asura's world. He's powerful enough to toss around planets and stars (I believe he was also able to make one star go nova, in their fight) but he should also be defeated by TTGL.