The official Pokémon Twitter account is teasing an announcement using words like "special" and "surprise" for Monday.

Presumably, the announcement will have something to do with Pokemon X and Y, but the posting is ambiguous enough where it could be about anything Pokémon-related.

Heads up, Trainers! We've got a surprise for you! Tune in Monday at 8 a.m. PDT for a special announcement!

— Pokémon (@Pokemon) September 14, 2013

For more Pokémon news, check out the the most recent trailer for Pokémon X & Y.

[Via: Siliconera]

Our Take
Most recent Pokémon announcements, teased or otherwise, have been the reveal of new Pokémon, evolutions, or little mechanical changes for X and Y. There was this mysterious teaser image a few weeks ago that we haven't learned anything about yet, so maybe we will learn something about that.