USSJ Trunks and USSJ Goku vs. Gohan

This is SSJ2 Gohan from Buu saga.

Speed is equalized.

So are we talking Cell Game Goku and Future Trunks using the Grade 3 forms? Even with equalized speed Gohan should still be stronger than them.

Gohan wins.

You have to remember that Piccolo only stated that G3/USS Trunks was more powerful than Cell, while he [Cell] was still heavily suppressing the bulk of his power.

This is the same Piccolo who, a bit later in the story, was absolutely awestruck when FPSS Goku displayed just 50% of his power for Korin.

Fast-Forward to the Cell Games, and everyone on the field was awestruck when FPSS Goku displayed his full power against Cell(who was STILL suppressing his power to some extent.)

Fast-forward a bit more in the Cell Games, and everyone on the field was awestruck when Cell finally displayed his full power against SS2 Gohan.

Fast-forward to the start of the Boo saga, and Goku believes that Dabura is on par with Perfect Cell, and then Gohan proceeds to fight Dabura fairly evenly.

So the scaling could honestly look something like: SS2 Gohan(Boo saga) ~ Dabura ~ Cell(100%) > Cell(slightly suppressed) > FPSS Goku(100%) > FPSS Goku(50%) > G3/USS Trunks > Cell(heavily suppressed)

Gohan, the only character in history to lose strength after going through puberty.