This is copied from the pikipedia. I cannot rewrite this due to my laziness. Sorry! Ultra-bitter spray is the purple colored spray that the player can get from 10 purple berries from the Burgeoning Spiderwort plant, or by finding a concentrated dose. These doses may be found by attacking Honeywisps, destroying eggs, fighting Doodlebugs, killing the insects at the Wistful Wild, killing purple Unmarked Spectralids, and defeating any petrified enemy.
Uses of the bitter spray[]
This spray turns most of the creatures into stone, and with that immobilizes them. When an enemy is defeated during petrification, it will crumble to dust and leave behind one dosage of a liquid, this being either nectar or a spray. Bosses, however, will drop five doses of liquid. The Titan Dweevil will drop ten doses. Plants and Candypop Buds cannot be petrified at all.
Petrifying enemies that are in the process of eating any Pikmin will make it possible to save those Pikmin from dying.
In 2-Player Mode, this spray can also be used to disarm the opponent's Pikmin by planting them in the ground, and thus reverting all flower- and bud Pikmin to leaves. Although the Pikmin a will automatically jump back out of the ground after a few seconds, they will not regain their buds or flowers.
The player can deploy Ultra-Bitter spray by pressing the Z button in the Piklopedia. This does not affect the Ultra-Bitter spray quantity in the actual game.