As part of the Pokémon 20th Anniversary celebrations various Mythical 'mon are making their way into the current-gen games. Mew was the first of the monthly distributions, and now Celebi is joining in.
Originating on the Game Boy Color, this modern iteration has the same moves as it did in Silver & Gold, including the ability to confuse poor old Pikachu below:
Its other moves are Recover, Heal Bell and Safeguard, and as you'd expect of the giveaway it's level 100. In this case the distribution is via the Nintendo Network, so you don't need to haul yourself to a store to get one. It's the usual process for receiving and accessing online gifts in X, Y, Omega Ruby and Alpha Sapphire, but if you're not sure of all the steps the official website has a handy visual guide.
This Celebi is available from today (1st March) until 24th March, so don't forget to pick it up.