Leaf Pikmin are the first Pikmin encountered in Pikmin and Pikmin 2. These Pikmin are slower and weaker than their bud and flower counterparts but bear no difference in immunity towards hazards. Whenever Pellets or deceased enemies are carried back to the Onion, the player gains seeds that are planted and start off as leaves. This happens assuming there is less than 100 Pikmin on the field.
There are few ways in both Pikmin games to upgrade Leaf Pikmin.
Letting Pikmin MatureEdit
If you leave a Pikmin sprout in the ground long enough, it grows to a bud Pikmin, and later a flower Pikmin.
Either by attacking Honeywisps, Unmarked Spectralids, Mitite, Ujadani, or just beating eggs, swarm Pikmin onto the Nectar they leave behind to transform your Pikmin into flowers in seconds. Again, Nectar can be found by breaking eggs, killing certain enemies listed above, or picking Nectar Weeds.
If you let leaf Pikmin get pummeled by a Mamuta, they will be instantly planted back into the ground and flowered.