Corona one is ok via some trial and error. I expected it to be super annoying but ended up liking it. Just had to redo it because certain Flans don't give a lot of points. So once you get the perfect timing (it's easy, by the way) you just go for the ones that give the best points. E.g. the pancake flan, the fastest flying one (it drops quick so you need to pull the trigger right away), the animal one, the water one.
I havent done all flan minigames yet but the Hercules one was the most annoying so far and easiest was the Toy Box one, which I expected to be so much more frustrating, whew!