Simple 2960 Tomodachi Series Vol. 4: The Trump is a Japan exclusive digital card game compilation that sports a Single-Pak link multiplayer mode for 4 players. There are 11 playable games in total (the 12th game is actually Solitaire so it isn’t accessible when linked) and you don’t really need to know Japanese to play.
The load time is longer because it is loading all 11 games into stand-by GBAs at once but this means players are free to select any game at any time without needing to restart the GBAs.