Once again, the time has come. After Cilan lost to her, Ash decides to battle Skyla next with a proper battle. However Skyla predicts she will win again using her "Air Battle" methods. The next day, the time for their battle was nigh. Will her prediction come true? No. And why is Ash's Tranquill glowing? Tranquill is glowing because it begins to evolve into Unfezant (Female Form).
Who's That Pokémon?: Swanna (US) Unfezant (Male Forme) (Japan)
A spectator for the Gym battle resembles Kenta from Beyblade Metal Fusion.
It's true that Skyla said about Ash using Tranquill against her Unfezant when its not "evolved" yet, but when he returns it back and summons out to battle her Swanna, it did evolved.
This is the second time Ash looked up Unfezant on the Pokedex from the last episode but the difference is it says "females flying skills surpass that of male Unfezants" instead of saying in full paragraph sentence.
This is the second time Ash tells Pikachu to lure a gym leader's Pokemon in with Iron Tail. First, was Elesa's Tynamo in BW052: Dazzling the Nimbasa Gym! after Ash's Pikachu created a smoke path just for Tynamo to home in on him but its been hit straight back with Pikachu's Iron Tail with a final blow. This time he used it on Skyla's Unfezant as Ash tells Pikachu to finish him off with Electro Ball which causes him to be knocked out.