Confirmed by CoroCoro Magazine's newest issue. A new Piplup Event will be distributed via Wi-Fi Connection which will have the Sing move and will be distributed from July 20th to August 9th.
Ribbon: Classic Ribbon
Date: 07/20 ~ 08/09
Game Distribution: Black 2, White 2
Distribution Type: Wi-Fi Connection
More Details as they come.
Got some details from the official site now:
Level 15, OT is リサイタル, Ability is Torrent, Hold Item is Metronome, Classic Ribbon, Cherish Ball
Moveset: Sing, Round, Feather Dance, Peck
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"Now that I've had my coffee..."