Could have been better.
Tatara's battle prowess really could have been expanded more.
They could have made him more analytical of powers, because he spent years imagining what kind of power he could have, he's able to analyze enemy powers at a glance and take advantage of their weaknesses.
He kinda did it with Mikan, although Aria gave him a rundown on Mikan's weakness, but Wind Child he did on his own.
Definitely could have been expanded.
This would tide over for a while until he gets a legitimate power up.
Problem is, how dafaq do you power up gel?
Maybe make him able to harden it so he can use as projectiles or coat himself with armor?
Author could have powered him up with his first encounter with Toya, when he saw Mikan injured and had that black aura around him, that would have been the perfect time to power him up.
Maybe his gel would change color to black when he utilizes it for other purposes
Or maybe he could have that one little girl who powered up Yowabi do the same for him
I could see him powering up his gel so much to the point where the only time we see him spew out his original white gel is for the gag moments
In any case, wasted potential