]The gardening mini-game gives about 700 to 800 Bun-Buns depending on accuracy which takes about 1 minute vs playing the basket ball mini game which can give maximum of 300 Bun-Buns without failing before getting your first shot which can take 50-60 seconds if you're good at it.
Hide and seek gives you 120 Bun-Buns Bun-Buns in 60 seconds and about 240 Bun-Buns if we go to the per minute (not including the 3 second timer at start).
And then 90 Bun-Buns in 30 seconds (180 per minute) for the Rock-Paper-Scissors Mini-game. Planting flowers gives the highest, it's pretty simple to cycle, you just gotta go into menu after completing the mini game and selecting the second check point in chapter two.

Should take about 10-15 minutes to get 10k Bun-buns, Good luck Gambling!