Mushroom

If you wish to gain an advantage in the Mushroom Showdown, I recommend keeping an eye on the newly spawned mushrooms at the daily reset time of 3 AM. Additionally, increasing your Pikmin's friendship and feeding them nectar to boost their work speed can more effectively shorten battle times. Are you perhaps still operating on a device with limited performance? This might also be one of the reasons affecting your snatching speed.

Befriend super pals who share mushrooms and wait for them to call for them. Most importantly: be fast! I still can't grab mushrooms sometimes, but I'm diligently practicing my speed...😅

Couldn't get it

Black bean

If you're going for the giant mushroom, just camp there. Go explore, see when the mushroom is cleared, and wait for it to respawn in 6 minutes. The rest is up to luck 🤣

Internet speed is the biggest trick...