A minigolf one could have a ball getting putt across the banner before having another one drop in in its original position again.
Ball Race could also have one with melons.
But I also like the idea of ones involving the plaza: a stream of tickets from the arcade, falling coins for the casino, swimming fish for the fishing pier, maybe bumper cars too?
I would love to see profile backgrounds based off the shops in Tower Unite, maybe you could use the store logos and Jazz them up a bit.
You could even do the gameworlds, minigames, and other plaza activates as well. Some could be unlocked via playing the game (like dino drive background) or part of the milestones