To restore to life all those who died since...

[Piccolo Daimao]

How would it be obvious? And what about my suggestion - that he'd wear a disguise and it would be only be revealed until later? And remember, in the original manga, when Goku said that he wanted Gohan to become stronger than him in the RoSaT, Gohan replied that in the future, he was a Super Saiyan but was still killed by the Androids. To which Goku responded that the future is different, and in that future, he didn't train in the RoSaT.

Different circumstances mean different power growth. Logic dictates that if Gohan doesn't have any sparring partners in the future, he'll be weaker than a present Gohan who has two sparring partners. Logic also dictates that if Gohan doesn't train in the RoSaT, he'll be weaker than a present Gohan who does.

When I said it would be obvious, I was thinking of him doing the exact same thing Trunks did - showing up, revealing he was a Super Saiyan, kill Freeza/Cold, and tell Goku he was from the future. If he did that, Goku and Piccolo would figure it out.

If Goku asked him if he was Gohan, he could just lie and say that he's not him, that Gohan was killed along with everyone else by the Androids, and that he's just another Saiyan that no-one knew about.

[Saiga]

How would it be obvious? And what about my suggestion - that he'd wear a disguise and it would be only be revealed until later? And remember, in the original manga, when Goku said that he wanted Gohan to become stronger than him in the RoSaT, Gohan replied that in the future, he was a Super Saiyan but was still killed by the Androids. To which Goku responded that the future is different, and in that future, he didn't train in the RoSaT.

Different circumstances mean different power growth. Logic dictates that if Gohan doesn't have any sparring partners in the future, he'll be weaker than a present Gohan who has two sparring partners. Logic also dictates that if Gohan doesn't train in the RoSaT, he'll be weaker than a present Gohan who does.

When I said it would be obvious, I was thinking of him doing the exact same thing Trunks did - showing up, revealing he was a Super Saiyan, kill Freeza/Cold, and tell Goku he was from the future. If he did that, Goku and Piccolo would figure it out.

If Goku asked him if he was Gohan, he could just lie and say that he's not him, that Gohan was killed along with everyone else by the Androids, and that he's just another Saiyan that no-one knew about.

His ki.

[Piccolo Daimao]

When I said it would be obvious, I was thinking of him doing the exact same thing Trunks did - showing up, revealing he was a Super Saiyan, kill Freeza/Cold, and tell Goku he was from the future. If he did that, Goku and Piccolo would figure it out.

If Goku asked him if he was Gohan, he could just lie and say that he's not him, that Gohan was killed along with everyone else by the Androids, and that he's just another Saiyan that no-one knew about.

His ki.

Oh yeah, I forgot about that.

[Silver Sinspawn]

There's two answers to this question.

1 is from a author's point of view which has been answered by Perfect.

2 is from the in-universe point of view. I feel the only person who'd come back in time would be Gohan and I don't think he's deceptive enough or would even want to wear a disguise or mask. He'd come, kill Freeza, give Goku the tonic and warn them about the artificial humans.

No one would stop Semi-perfect Cell from absorbing 17 and 18. Piccolo and Future Gohan would go into the ROSAT, Goku and present Gohan would go in together. They'd come out, Goku would give up, then die after which little Gohan would go nuts and kill Cell after which Future Gohan goes back in time and kills Imperfect Cell easily, bones future Bulma after which we'd get Grunks. Okay everything minus that last part.

Grunks? You're crazy, man. It'd clearly be Gohunks

[Gonstead]

Nah, I'd say it would be Truhan.

[Silver Sinspawn]

Come on, lets settle this. Trogankshu