If you've finished the main story of Pokemon Sun and Moon you can grab yourself a free legendary.
Pokemon Sun and Moon has only been out for a few weeks but the first legendary distribution event for the game has kicked off. If you've already finished the main story of the game, you can get the legendary Pokemon Mageara simply by clicking this link and scanning the QR code with the in-game QR code scanner.
Mageara is a steel/fairy type with the soul-heart ability, and best of all, comes holding a bottle cap - a rare item that allows players to use the "hyper training" feature that can alter a Pokemon's Individual Values (IVs).
Don't worry about rushing through the game to get her though, Nintendo has stated that the QR code will work "indefinitely", so Mageara will be waiting for you whenever you get around to finishing.