Fantina says, "Never give up, never surrender!" in D/P/Pt, which is a quote from Galaxy Quest. There are also a lot of 4chan references in D/P, like the youngster in Oreburgh calling the player a "noob."
There are loads of pop culture references in B2/W2, such as:
-Billy Jo, Roxie's bandmate, is named after Billy Joe Armstrong from Green Day
-Some of Pokestar Studios' movies are based on other movies, like Enspoinklopedia Brown (Encyclopedia Brown), Rip Van Dwebble (Rip Van Winkle), Galvantula's Travels (Gulliver's Travels) and Snivy in Ivyland (Alice in Wonderland).