Fancy Pattern Vivillon available until end of July
Pokemon Events — 25 July, 2014
This one is called the Fancy Pattern Vivillon and it comes with an exclusive move, Hold Hands, which increases Pokémon's happiness (but can only be used in double/triple battles).
It is available via
Mystery Gift on the main menu, then
Receive Gift, then
Get Via Internet. The event runs from July 7th to July 31st so make sure to get it while you can!