It appears that owners of 3DS, 3DS XL and 2DS will not be able to use miiverse whilst playing Super Smash Bros, so no uploading of screenshots whilst playing the game.
It seems that those who own the New 3DS and New 3DS XL will not be affected, here is a translated quote:
“Miiverse cannot be run while this software is being played, so posting screenshots to this community is not possible. When using this software with the New Nintendo 3DS or New Nintendo 3DS XL, Miiverse can be used while playing.”
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