And by being a magnet, he meant trouble always seemed to find him, not that he was literally drawing evil after him. The Red Ribbon Army wasn't specifically after him in the beginning, nor was Piccolo, hell, even Freeza wasn't after him, but it was their bad luck that he happened to be on the one planet they needed to go to. I don't think he was simply referring to people who wanted revenge on him. Even if there were any left, Gohan could've taken them. That's not dumping anything on Gohan's shoulders. Gohan may not have been a fighter by nature, but he didn't hold it against anyone that once in a while he would have to defend his values.
Trunks wasn't that cocky, immature, sure. Did you see how determined Goten was after Buu killed his mom? When Goku was gonna train them, they showed that they were ready and willing.
Goku could've defeated Vegeta EXCEPT for the fact that Toriyama didn't think ahead and created a plot hole.
If Kaioshin had divulged the full truth, who knows what would've happened.
GOku's not omnipotent but he had a clue, he knew the power of fusion.
Gohan did outclass Cell, Gohan ONLY held back because he was worried about the damage to the planet. Even if it was just due to the momentary destraction, he would still have to be a lot stronger than Cell to kill him.
{Goku:} I understand now! Gohan, you're worried about hurting the planet! That's what's holding you back! Don't be concerned about that! We can reverse any damage with the dragonballs. Now concentrate!
Yeah, the reason is he doesn't think ahead.Toriyama put that line how Goku could have beaten Fat Buu in the manga for a reason. It's not like he NEEDED to put that line in there for story's sake, Toriyama wanted it to be established Goku could have beaten Byy but wanted the kids to do it.

