In a recent interview conducted by Gamasutra business editor Colin Campbell, Pokémon Marketing Director J.C. Smith explains how the company keep consumers engaged, even when there are no new game launches.

"We just give them fodder. The community already talks. It's part of what's core to Pokémon. The fan sites out there help spread the word for us."

He adds, "For us it's about giving our fans something fun to do in between game launches. That's my bread and butter. That's exactly how you should treat your fans. Giving them activities and things that they can continue to do while they're waiting for the next version of the game or the next world to be released." (Pokémon Marketing Director J.C. Smith)

Source: http://gamasutra.com/view/news/35013/Interview_How_Pokemon_Keeps_Marketing_YearRound.php