DB Daima's characters must be much stronger than we think.
Gomah saw in Episode 1 scenes of the Majin Boo Arc, I could see and realize that Ultimate Gohan and Gotenks SSJ3 were stronger than Goku SSJ3. He also saw the Genkidama that eliminated Kid Boo.
In an Episode Gomah commented that if he had known that Shen Long could only fulfill 1 wish, he would have preferred to ask for the 3rd Evil Eye instead of turning the Z Fighters into children. This means that Gomah thought that by possessing the 3rd Evil Eye, he would have been invincible, despite having seen Ultimate Gohan.
When Gomah possesses the 3rd Evil Eye and began to be surpassed, at no time did he think that the 3rd Evil Eye was less powerful than he thought, rather he was impressed by how powerful the Z Fighters were.
Gomah then strengthened any amount as the fight progressed.
Goku surely got a lot stronger between his fight against Tamagami and Majin Duu after seeing his performance against both of them.
In one part, it was said that Gomah in Episode 17, Gomah Initial, was more powerful than any previous villain, that is, he is stronger than Gohan Boo. Kid Goku SSJ3 surpassed that version of Gomah and Gohan Boo.
Adult Goku and Vegeta are too powerful.