It is sort of uncertain if the battle happened or not in the context of that issue but the fact that after the K-T Extinction happened, Godzilla wakes up to present day with a piece of Stranger's tail which leads some credence to the battle in the Cretaceous. But as I said it is not explicitly stated in the issue if the battle did indeed happen or not.
couldnt ares easily cut his way inside him? and kill him from within?
the guy has an admantine axe that cut through virtually anything , even void sentry
From the posts that Colossus Big C has been making I take it he hasn't much in the way of knowledge considering Godzilla in movies and in comic form. To add further to Endless Mike's mentioning of Godzilla's superfast regeneration and internal nuclear reactor of a heart, Godzilla's body itself has incredible durability to all conventional harm and would not be cut real easily and even if it was, any wounds would heal up just about instantly. Oh and it would be funny to have Godzilla be given the Power Cosmic on top of the already immense nuclear power he already has though I'd wager Galactus would not want to give a creature that kind of power.
I've never thought about that possibility, that Godzilla could utilize the nuclear power within the sun to essentially sun-amp. I've not ever seen that possibility brought up in any conversation about Godzilla's powers on any kaiju websites I've visited over the years.
Godzilla would more than likely drain Hulk dry completely and Godzilla vs Hulk has been already done on here and jinzin totally made the case for why Godzilla epicly pwns the Hulk due to superior regeneration, radiation draining, and everything else Godzilla has over Hulk.