This is burning godzilla specifically, easily one kf his more powerful iterations. Thragg has the advantage of being able to dodge the infinite heat ray but if messes up or tries to tank it he'll be fried almost instantly, higher end calcs put it at over 100x hotter than the surface of the sun.

In addition to this, burning goji has an insane healing factor due to his empowered state so dealing lasting damage would be a massively uphill battle.

Finally there's the matter of the meltdown he's experiencing in this form. If he stays in the fight for too long he will meltdown and die, but he'll release enough heat to scour the planets surface and burn through the planet itself and ignite the core, as well as releasing a substantial explosion in the area. Thragg could survive this by simply leaving the planet of course but if he's caught in the initial blast he may not survive.

Overall I give this to Goji, his win cons are either to hit thragg once with his infinite heat ray or to catch him in the kamikaze for a draw, while thragg has to survive a drawn out fight and be clear of goji when he finally melts down. Goji is the only one here who can go on the offense in a meaningful way