Aquaman slaps them with 2 huge ass salmons XD
Aquaman is ruler of the ocean. The ocean is like 70% of the planet. That means his powers are viable almost everywhere and he has access to his source of energy almost everywhere. He is in no way useless.
But 95% of crime takes place on land LOL
Jk, yeah he's not useless.
And Tenten just doesn't get enough screentime.