Older models will not be able to access Miiverse features while playing the game.
Key Super Smash Bros. for 3DS Miiverse features have been revealed to be compatible with only the New 3DS models coming in October, posters at NeoGAF have discovered.
Players have discovered that trying to enter Miiverse while playing the game will get them an error message. The same goes for those who try to enter the internet browser, as well. The Japanese Miiverse community description of Super Smash Bros. for 3DS, however, suggests the Miiverse features will be accessible if playing on New 3DS models.
NeoGAF users have put forward a workaround where in-game screenshots can be saved onto the SD card, then uploaded manually using a PC.