There is a Maximus Cup this weekend in Tetris 99 on Nintendo Switch. The 42nd Maximus Cup is for the Switch game Splatoon 3. By getting 100 points, you can unlock a Splatoon 3 theme which includes sounds and a background.
The side quest, as ever, is to try and win. unfortunately, i didn't manage to make it to the top 10 at all during this cup. in the first couple of games i managed to get into the top 30, with the first game being especially difficult. but other than that, i wasn't able to score too highly.