In the end, they can agree to disagree. Yamamoto's flames are versatile, and Gokudera's got his own rain flames to play with and compare to his storm flames. He sees how they react when combined, and while it is great in protecting people, Storm flames literally eat away and destroy other flames.

Haha! Take that, Yamamoto! Gokudera's stomping appeared to give him some advantage, and he's searching quietly until he glances over at... whatever that thing is in Yamamoto's hands.

Not wanting the other to think he's trying to copy his technique or whatever, Gokudera turns his back to him and crouches, trying to be as still as possible until something moves across the top of his foot. He lets out a totally mature shout of surprise and kicks a crab out of the water. At least that's normal. It doesn't count though, right?

"Ugh!!" Aggravated, his hands slide back into the water and he can see fish, so he's just going to spread his arms wide to block out any means of them swimming around him. Gotta... herd them into shallower water? Sounds like it should work... And the fish are swimming away from him and closer to the beach.