Oh that's great news! Did they say if the demo gives out the panda costume as well?
The actual physical game comes with two codes for the move in edition, which has the panda suits. So, you could redeem one of them and then get your two panda suits. However, a standard demo will available to everyone, but it doesn't have any panda suits unfortunately.
This is exactly what they said
"While I can understand your disappointment at not being selected for this recent promotion, I wanted to let you know that the Move-In demo will also be available upon purchase of the full version of the game.
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. The Move-In demo will also include the two Panda Suit bonus items.
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. Digital copies of the game will have the download code on the Nintendo eShop receipt. Physical versions will have two codes included in the packaging.
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. Save data from the Move-In demo (including characters and the Panda Suit bonus items) will transfer to the full version.
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Additionally, a standard game demo will be available in the Nintendo eShop after Tomodachi Life is released."
Btw, I believe there are panda suits in the actual game, but they are black and white (standard color).