It appears that Game Boy Advance games to be released on the Wii U virtual console will lack support for multiplayer.
The service is set to go live in April, with a range of Nintendo favourites already confirmed for release throughout the month like F-Zero: Maximum Velocity and Mario & Luigi: Superstar Saga.
However, games that had supported multiplayer (via the classic Nintendo Link Cable) will not maintain that feature in the Wii U Virtual Console re-release. Listings on the Nintendo of Japan website point towards single player only for these games.
Should Nintendo have enabled multiplayer with GBA games - perhaps through Wii U to 3DS connectivity?