Sixteen had used his bomb earlier?

[Hector]

Let's say that, when Cell has just become perfect, Sixteen decides to self destruct with him. The blast kills everybody around (Krillin, Vegeta, Trunks).

Scenario 1: Cell dies.
Scenario 2: Cell survives with his SPC zenkai.

 

[Warmmedown]

Scenario 1: Ebryones brought back, Krillin still ends up with 18. Gohan doesn't go Ssj2, but Goku keeps training with him and Gohan still gets stronger, but still doesn't have Ssj2 in the Buu Saga probably, unless he gets it at Apologise vs Videl (spopo autocorrect). If he has Ssj2 he whoops Dabura. GOKU doesn't have ssj3 and gets whooped on by Vegeta (can't convince him to stop fighting either). Buu Wrecks everyone (vegetable vs Goku is enough to revive him). Gotenks Wrecks everyone, gets absorbed and Gohan Wrecks Buu. Or maybe the Supreme Kais etc send Gohan to fuse with Goku and he Wrecks Buu instead of Gotenks.

 

[Warmmedown]

2: Goku fights Cell, gives him a senzu bean, Gohan fights refreshed Cell but gets whooped on. Future Trunks comes back in time to and shows Gohan video of his future wife he'll miss out on, Gohan is only 11 so isn't aroused enough to care. PICCOLO fakes his own death gohan goes Ssj2 and kills Cell with a masenkohamehamehameha followed by a wolf fang fist going through the beam but left hand is holding a kienzan and he makes a Tobey Maguire pizza reference but nobody gets the joke so he becomes a recluse.

 

[SSJ2]

1. The Cell arc ends with Vegeta, Trunks, Krillin being brought back to life. It's debatable whether or not Gohan would continue training if Goku is around. I feel as though he might keep up with it, but the question is would any of the Saiyans unlock SSJ2 without having seen the form? If they do, the Boo arc would look completely different. For one, nobody would go to the Budokai if Goku was alive, so it's debatable if Boo would ever get revived. Even if he did, there's no chance he'd be revived at full power, so the 3 SSJ2s would be able to take care of him.

If the Saiyans don't learn SSJ2, they would die to Boo unless they are able to acquire the form.

2. Cell destroys earth. He'd be too strong for Cell Games Goku and would likely become angry with the tournament and blow up earth as a result.