Antartica is replaced with...

[HollowKyubi Espada]

These different nations replace antartica, what happens when they are discovered? (They are discovered the same antartica was, and for the sake of the scenario they didn't bother to "seek" us out.

1) Elemental Nations (Avatar: TLA, only Earth and Fire Nation)
2) Elemental Countries (5 Kage Summit)
3) Hyrule (Twilight Princess)
4) Kanto/Johto (Pokemon)
5)Hoenn (Pokemon)
6) Western Continent i.e. Shinra (Final Fantasy VII)

And how do they affect us?

[The Drunkard Kid]

Avatar: Everyone that isn't a Polar Water Bender dies of Frostbite, eventually.

[Forgotten Entity]

They freeze over.

[HollowKyubi Espada]

I meant that their environment stays the same as it is shown. How would them being on our world affect us?

[Wjowski]

Avatar: Everyone that isn't a Polar Water Bender dies of Frostbite, eventually.

Except the firebenders.

[Omegalith]

I meant that their environment stays the same as it is shown. How would them being on our world affect us?

Well, the environment would be screwed over completely causing rampant worldwide hurricanes and such.

[Guy Smiley]

Well, Pokemon would affect things long before the country was discovered. A lot of those things have migratory paths that would take them around the world, ravaging the local ecology as they go. (Hey, a Dragonite's gotta eat, y'know!) The planet would probably have mostly Pokemon-related wildlife.

Hyrule? Probably less so, but you still get things like Poes and a real, working Triforce hanging around.

Shinra takes over the world, with their super-advanced (especially for the era, considering how long ago Antarctica was discovered) technology and their access to Materia (I guess they have some sort of localized Lifestream or something?)

[Omegalith]

Hyrule? Probably less so, but you still get things like Poes and a real, working Triforce hanging around.

Hyrule has a truly ridiculous variety of Undead lurking around underground and in forests.

Also giant hell spiders.

[Guy Smiley]

Hyrule has a truly ridiculous variety of Undead lurking around underground and in forests.

Also giant hell spiders.

Oh, sure, but a lot of that is effectively landbound - the rest of the world isn't going to see that stuff crossing the oceans as a matter of course. (Well, I suppose the undead might decide to go on an ocean-floor walk, but...)

I suppose it would be enough to make the explorers turn right around and go home, though.

Of course, since the Hyrule from various games is all part of the same forked timeline, you probably do have things from other games like Wind Fish and Tingle hanging around the periphery...