Junichi Masuda has confirmed that he will be on this weeks Pokémon Smash #73 - The King of the Forbidden Forest! Fushigibana!! / Both Robert and the International Division Participate in the Pokémon Quiz Caravan in Sendai, Miyagi Prefecture / A Rayquaza Duel in Group Member Baba's Elite Four Battle! (禁断の森の王者！　フシギバナ！！ / 宮城県仙台市でポケモンクイズキャラバン、ロバートやインターナショナル部も参加 / 四天王バトルは馬場隊員、レックウザ対決！) despite the previews or previously released information about the episode not even mentioning it at all.

On February 7th, 2010's episode of Pokémon Sunday, episode #277, Junichi Masuda appeared on the show to introduce new games that GameFreak had been working on for four years. The titles of the games were not announced on that appearance but they ended up being Pokémon Black and White (ポケットモンスター ブラック・ホワイト). He also revealed a silhouette which ended up being Zoroark.

This time last year on Pokémon Smash #21, GameFreak Game Designer Shigeki Morimoto (森本茂樹) was on the show but he did not announce anything and just helped the Smash crew with their battling skills. Masuda insists though that he "will be making a VERY important announcement, so be sure not to miss it!! Watch it live on TV!. Below is Junichi Masuda's blog post.

HIDDEN POWER of masuda Director's Columns - No.221 (English)

IMPORTANT NEWS!! On this coming Sunday, Februrary 26, 2012, from 7:30 A.M, I, Masuda, will be appearing on TV TOKYO’s Show, “Pokémon Smash!”

Not only that. And there… I will be making a VERY important announcement, so be sure not to miss it!! Watch it live on TV!

And, for those of you who can’t watch television on live, I will announce the same information right after the show via twitter!! Everyone, I hope you all enjoy the show!! Ciao!

*TV program “Pokémon Smash!” can be seen only in Japan.

Source: http://www.gamefreak.co.jp/blog/dir_english/?p=497