What is a hidden ability?

Question

I often read about something called Hidden ability. I know that each Pokemon can have 1 of 1 or 2 abilities, however, I noticed something called Hidden Ability, wonder whats that.

these are examples.
1-Both Pikachu and Seaking have Lightningrod.
2- Ludicolo having Own Tempo.
3- Bastiodon having Sound Proof.
and many many others.

Source: Bulbapedia ( check every pokemon and see the ability there )

How do they function in battle? is it as obvious as normal abilities?

thank you so much.

Answer 1

Those are Dream World abilities that are accessed by special means in Black & White's Internet-based capabilities.

Honestly, I don't know all of the details of the Dream World, but look it up in Google, and read up on it, if you're interested. =D

Comments

Oh, that makes total sense now! that explains why some Pokemon have V Gen. abilities. Actually, I know quite a bit about the Dream World but I rather not bother myself yet with the Japanese one, its not long til we get official English well-written info. :D. So yeah, we are on the same page, thanks, question answered.