The official Pocket Monsters Best Wishes website has announced that a new ending will air on the April 7th, 2011 episode BW29 - The Horror Stories of Hitomoshi Mansion! (ヒトモシ屋敷のこわ～い話！). The ending is called "Can You Say the Pokémon? BW" (ポケモン言えるかな？ＢＷ). The song has a very fast tempo like the previous naming songs. A couple screenshots from the ending were posted on the official site and can be seen below.



Sources: http://www.tv-tokyo.co.jp/anime/pokemon_bw/news/index.html & http://www.tv-tokyo.co.jp/program/detail/21304_201104071900.html