There is currently no info on any future events for a Regigigas.
You had to get it in a Nintendo event for D&P, then trade it over.
You have to go into Snowpoint Temple but you first need to get the National Pokedex. Once you make it to the bottom, regigigas is there but he is a statue. You need a Nintendo event to be able to get all regis and regigigas.
nobody is sure check Nintendo.com/eventsmain It is in japan from June 20th to august 31st they are giving away Regigigas in a cherish ball
This month you can get Shaymin in the US and next month you can get Regigigas, the Shaymin event is February 8th-14th and the Regigigas event is March well I forget when it starts, but it ends on the 21st.
Giratina Palkia Dialga Mesprit Azelf Uxie Cressillia Darkrai(Nintendo Event) Manaphy(Download from Pokemon ranger) Phione(Breed Manaphy) Regice(Nintendo Event) Regirock(Nintendo Event) Registeel(Nintendo Event) Regigigas(Take the Regi-trio to Snowpoint Temple) Arceus(Nintendo Event)
The event happened a while ago over Nintendo wfc there is no way to catch it in game...
As far as I know, it isn't possible to wake up Regigigas without Regice, Regirock, or Registeel, and the only way to get those three is to have a Regigigas in your party that was obtained by Nintendo Event. Hope this helped!
You could only get the movie Regigigas through special Nintendo events or through hacking the event Pokémon or by trading with someone else in order to get it.
For Regice, Regirock, and Registeel transfer from Ruby/Sapphire/Emerald And get them at Pal Park, or you could use an action replay but that is cheating.Otherwise you would need the Regigigas from the event. For Regigigas, you need the other Regis and go to the temple in Snowpoint city.
the arceus event
Probably October 30th.
at toysRus they have a free lvl 100 regigigas ends march 21