So I got this thingy

What tf does the Dream Mist item do?

Gives a pokemon it’s hidden ability when given to the Dream Guru in Gaea Town.

Huh. Neat. How can I get more?

Pokemon Championship in the Battle Frontier, cooking it in Selene town with an IV stone and 3 rare candies, and just talking to people.

I heard you can get some in the Dream Realm as well. Is that true, and if so, how?

It has an average chance of being found in the Cortisol Road Hidden Grotto.