For those of you in the US with a 3DS, Nintendo's currently distributing a Special Mii of Shigeru Miyamoto through Spotpass. Miyamoto's Mii is level 5 (for you Find Mii/Find Mii 2 players), and has all of the puzzle pieces for the puzzles currently available for the US, including the pink Streetpass-only pieces. This is being done as a promotion for Luigi's Mansion 2, and I don't know how long the promotion will be available.
If you don't automatically receive the Special Mii, make sure you have Spotpass enabled, especially for the Streetpass Plaza; then, try opening the Plaza, then exit it (with the Home button, then close the Plaza), and wait for a bit.
(Note: The promotion has most likely ended by this time; I've read that they usually only last a few days, though nothing official.)