Birthday

Not to be confused with It's My Birthday.

"Birthday" by Katy Perry is featured on Just Dance 2015 and Just Dance Now.

Appearance of the Dancer
The dancer is wearing a pastel-schemed costume. She is wearing a pink and sky blue top with sprinkles, a yellow and pink layered skirt, yellow polka-dot stockings with pink cupcake prints and blue high heeled boots. She has long marigold hair tied in a ponytail braid and is wearing a floral wreath made of teddy bears and button flowers. She is wearing very heavy makeup consisting of blusher and eyeliner. She also looks Asian.

Background
The background also has a pastel scheme. There are also pictures of cake and confectionery appearing. It is supposed to give the dance a Birthday feel.

Gold Moves
So far, there are 2 gold moves for this song:

1 & 2. Throw both of your arms up in the air while you lift up your right leg.

3. Jump up and hold both hands out as in confusion.

Mash-Up
An Ubisoft staff confirmed the Mash-Up with a photo. The picture has got removed.

Trivia

 * This was revealed in the ESRB's rating summary. The following 3 lines are referenced as suggestive:
 * "Pop your Perignon"
 * "So let me get you/In your birthday suit"
 * "Boy when you're with me/I'll give you a taste"
 * This is the 10th Katy Perry song in the series, The first being Hot n Cold in Just Dance, second being Firework in Just Dance 2 (as a free DLC), third being California Gurls in Just Dance 3, fourth and fifth being E.T. and Teenage Dream respectively as Just Dance 3 Best Buy exclusives, sixth being Part of Me in Just Dance 4 and Just Dance 2014 as a DLC, seventh being I Kissed a Girl in Just Dance 2014, eighth being Roar also as Just Dance 2014 free DLC, and the ninth being Waking Up in Vegas as a Just Dance 2014 Popchips exclusive.
 * They use a move from Pound The Alarm at some moments.
 * "Birthday" in "birthday suit" will probably be censored (despite the ESRB website fully saying it), as it was also removed in The Lazy Song, because a birthday suit refers to nudity.
 * The dancer's face can be seen clearly.
 * The dancer smiles a lot, akin to Take on Me and Price Tag
 * Just Dance 2015 will come out in October, which is the same month as Katy Perry's birthday (Oct 25). The fact that this song by her is birthday themed will be featured makes it a huge coincidence.
 * Unlike other dancers with makeup that is hardly visible in game, this dancer's makeup is clearly visible.
 * She might be the same dancer as P2 from Nitro Bot.
 * The dancer looks like a clown because of her make-up and costume.
 * Birthday has a move similar to Primadonna. The move is that both coaches turn to each of their sides and "blow" the candles and chandeliers respectively.
 * A mash-up for this song has been leaked.
 * This dancer's makeup scheme makes her face very visible, which is also happened to Break Free