One (far out) explanation for Gohan not using the Ultimate form again is that all the Saiyans had the ritual done! The new realm of power overwrit that transformation, just as for Goku that his SS is just a bit stronger than base now and he won't go SS2 or 3 again; absorbing the realm of God power completely changed his ki, and for Gohan erased Ultimate.
Of course, from BoG, we know that a Super Saiyan starting from the same base level can be stronger than a SS3 (
), so maybe that's not necessary and Old Kai was just wrong, and Super Saiyan actually is the best way of doing things. Gohan realized SS is stronger after watching Vegeta, ahuh ahuh (Pennywise laugh)!
EDIT:
Zombie wrote:
But I wonder, what can he do? Even bulked up he still wouldn't crack 200. All of Freeza's goons should be in the 1000's.
We only saw a few goons of Freeza's on Namek. For all we know, they were relatively speaking, pretty strong to even be in the 1000s. Though Dodoria, Zarbon, and the Ginyus (who are outright stated to be elite) are much stronger than that, and the few "lower levels" which Freeza brought on this special mission were over 1000, in the broader perspective; out of the presumably thousands upon thousands of troops Freeza has across his empire, maybe most of them don't hit the 1000s. There might be thousands of troops in the 100s in battle power picked out of billions upon billions of races who don't really have average powers much higher than humans.