In the new ending theme Ash has an Unfezant, which is a strong indication that in a futtre episode Tranquill will evolve, but this has yet to be proven. Until then, No one is allowed to change the title of the page until the evolution has occured. This also goes for his Swadloon and Tepig.
It was revealed in the promo of BW070 that Ash's Tranqull will evolve into Unfezant Female form. However, the episode won't air until next week so no one is allowed to change the title of this article until then. Thank you.