Gohan has hidden powers that reveale themselves when he gets angry, this is how he beals Cell.
If I had to guess, I would say Gohan is just better than Cell!
In Season 10 episode 16 of Dragonball Z, Gohan loses to Cell.
In Dragon Ball Z episode number 181 titled "The Strongest Successor... His Name is...
At the chronological age of ten (biologically he was 11) Gohan fought Cell. !
The name of the "Dragonball Z" episode where Gohan beats Cell is "Dragon Ball Z:...