@ImDictatorBowDown: Recall that the fight depleted enough of Cell's ki reserves where Goku gave him a Senzu Bean before fighting Gohan so he could be at full strength. I wouldn't necessarily say Cell was holding back in his fight with Goku.
@BloodSprinkles: Goku was weakened from his fight with Perfect Cell and never bothered eating a Senzu Bean after the fight which was why he was getting creamed. Trunks, Piccolo and Vegeta were strong enough where they could fend off their attacks, but not enough to get an advantage on them either. In comparison against Broly, all four were getting creamed without being able to hold up any kind of defense against the LSSJ.