Going by Pokemon terms, the H-bomb would just be the move
Explosion of a
much wider radius. It still retains the Normal-type properties of the move Explosion. Absol would likely be able to escape as it can sense and detect disasters in advance, and I'd assume that a nuclear explosion would be classified as some sort of disaster.
Whether the H-bomb affects Ghost-types is whether you classify it as a "Fire-type move" (due to the "extreme heat" you mentioned) or a Normal-type move (due to its extreme likeness to the move Explosion), in which the H-bomb wouldn't do a lick of damage with the latter classification. Since the H-bomb is essentially the equivalent of Explosion with a tremendous amount of base power, I still maintain that Ghost-types wouldn't be affected by the nuclear explosion. Technically, Ghost-types shouldn't be affected by
anything at all by virtue of being
ghosts, but such an immunity to all types would essentially make them broken by Pokemon mechanics. Thus, they are inexplicably weak to Fire-type moves in the games.
Earthquakes and
Hurricanes can level and destroy cities, yet many Pokemon defend against those events as part of their daily training regimen..
I never said that Protect "equals" God; I'm just pointing out the potency and benefit of the move Protect. Not only can it protect against damage from regular offensive moves, it provides protection from
one-hit knockout moves. OHKO moves essentially cause
infinite HP damage, because no matter what a Pokemon's HP stat is, if the opponent successfully connects with an OHKO move, the defending Pokemon will get KO'd period. As powerful as an H-bomb is, the amount of damage it could do is finite, so Protect can and will still serve its purpose of negating
all damage. If Protect can ward off infinite-HP-damaging attacks, it sure as heck can provide protection against an H-bomb.
As for the use of Psychic...I'll admit that it does depend on the strength and limits of the individual Pokemon. But who's to say that a bunch of Alakazam (with a 5000-point IQ that could come in handy) couldn't combine their Psychic abilities to move the H-bomb a far distance? Heck, they could probably find a way to render the H-bomb a dud and somehow prevent it from exploding in the first place.
Additionally, Aura-using Pokemon (which aren't all legendary, btw) can employ
this technique as another counteracting measure against the H-bomb:
Finally, Golduck (
and several other Pokemon) with Damp ability says hi.
But yeah, seeing as pretty much
every Pokemon withstand intense burns, electrical shock, sheer cold, explosions, crippling poison, earthquakes, and the like on a daily basis (things that
us humans can't even do on a regular basis), I'm pretty sure most, if not all, of them could handle and/or nullify a "freaking bigger" Explosion...