Bulbmin

Bulbmin (adults:, juvenile: ) are a parasitic species of Pikmin in that infect Bulborbs, hence the name. They are only found in caves and there is no way to store them, meaning Bulbmin can only be used in the cave they are found in. They are resistant to all four hazards defined by the game, and are one of the only ways to gain Pikmin in a cave, making them a valuable asset.

Uniquely for a Pikmin type, they start out as enemies when they appear in a cave. An adult Bulbmin, closely resembling a Red Bulborb, is followed by up to 10 juvenile Bulbmin, which take on a more unique appearance (having completely black eyes rather than the blue or purple eyes of the dwarf and adult Bulborbs, uniquely proportioned and colored legs, and relatively fewer and larger white spots which are positioned differently than those of other bulborbs) with a stem and leaf (or bud or flower) atop their back. They can be found wandering the floors of certain caves and behave much like the Spotty Bulbear, patrolling an established path. The adult Bulbmin is quite aggressive, but can be defeated quickly. When the adult Bulbmin is defeated, the juvenile Bulbmin will panic until whistled, at which point they will join the player's squad. At this point, they can be used like normal Pikmin. When the player uses a geyser to exit the cave, all Bulbmin in their squad are left behind.

As Pikmin
As Pikmin that the player's leaders can use, the Bulbmin are identical to other Pikmin types, but look like Bulborbs and sound different. They have average capabilities in terms of mobility and strength, but are immune to all elemental hazards (fire, electricity, water, poison) and non-elemental hazards, and also cannot trip. As beneficial as their abilities may seem, they cannot leave the caves with the group, for an unknown reason. Instead, they stay behind and watch the leaders and fellow Pikmin leave. Because of this, they will not count towards the overall Pikmin count, although any deaths do count towards the lost Pikmin total. Them being left behind when a cave is exited does not count as a death, however. This makes them ideal for use in Candypop Buds.

These Pikmin infect Bulborbs and take control of them, but it is implied by Olimar that they can take on other hosts as well. There is no information regarding what Bulbmin without a host actually look like. It is possible that they are green, since they appear as green dots on the radar, and since their leaves glow green when idle. Although they may also be orange, given the color of their stem, as well as the color of the conical aiming cursor when a Bulbmin is in hand, and the color of the trail they produce when thrown. That said, what is known is that their buds and flowers are white, just like Red Pikmin, Yellow Pikmin and Blue Pikmin. The only way that Bulbmin can be killed before ever being whistled is if they are crushed or they fall over the side of a level into the abyss when shaken by an enemy attack, explosion or other sufficient force. When that happens, their deaths will not count for the player's death tally.

Up to 10 juvenile Bulbmin can spawn with an adult Bulbmin, but they count towards the one hundred Pikmin limit when they spawn, so if the squad has more than ninety Pikmin when entering the sublevel, not all of the juvenile Bulbmin will spawn.

Pikmin
To ensure a low Pikmin loss, if not zero, wait until it approaches the active leader, then throw Pikmin rapidly on top of the beast, further to the back than the front. If done correctly and with good aim, it should shake them off and turn around slowly: it has been distracted, leaving a large time gap in which to swarm it. Do it, then, and it should die before any of the Pikmin it manages to swallow do. Also if it is attacked by other Bulbmin it will hesitate slightly before attacking allowing more time to deal damage.

As extra precautions or for an easier fight, use Purple Pikmin or an ultra-bitter spray if it captures any Pikmin.

Leaders
Approach the Bulbmin like a roaming Bulbear, attacking it from behind and avoiding its bite. Although its health is significantly lower than a Bulbear's, it can still take a substantial amount of time to kill without the Rocket Fist.

Trivia

 * In an official Japanese poll, Bulbmin and their juveniles were ranked as the most popular Bulborb enemy in Pikmin 2, even above the Dwarf Red Bulborb and Red Bulborb.
 * The only place where Bulbmin can be buried – and hence, the only place where one can observe Bulbmin with buds – is the Frontier Cavern, on its fourth and fifth sublevels. Swooping Snitchbugs can plant them in the ground on the former and they can be planted by Mamutas on the latter.
 * If the game is altered such that it allows Bulbmin on the surface, they will take refuge in the ship's storage when the day ends, just like Purple Pikmin and White Pikmin. They will still count towards Olimar's Pikmin count, but they cannot be taken out of the ship the next morning. Like the other ship-dwelling types, they will take fallen foes or pellets to a random Onion and will tote any other objects, like berries, to their correct location. They will still be immune to all hazards.
 * Although all Bulbmin are immune to poison gas, the adult Bulbmin will take a fair amount of damage upon eating a White Pikmin.
 * Bulbmin can actually be found in the game files of Pikmin 3, despite them being absent in-game. Because of their model being identical to the one in Pikmin 2, it can be assumed that the idea of them returning was scrapped early in development.
 * It seems that the only Bulborb that the Bulbmin tends to take hostage is the Red Bulborb, even when it would make more sense to take control of a Hairy Bulborb in cold caves. This is generally in line with real-life biology, where a parasite will be specialized to take only one specific species as a host.
 * Bulbmin are the only Pikmin that were created before Super Smash Bros. Brawl and do not appear in that game in any way, or in any other subsequent Smash title.
 * A Bulbmin appears on the New Play Control! Pikmin 2 Channel Screen.
 * Strangely enough, the young Bulbmin do not die when caught in an explosion while under the control of the mature Bulbmin. However, when under the player's control, they can die by explosions. This is more of a useful tip, since the mature Bulbmin can die from it, and the young will remain fine.
 * When juvenile Bulbmin perish, their souls appear as any other enemies' souls, not as Pikmin souls. This may likely be due to how the Bulbmin find a bulborb host, in which the host ends up losing its life as well.
 * Bulbmin are the first type to have a unique voice, and are the only type with unique voice samples in Pikmin 2
 * They, along with Breadbugs, can be cannibalistic, as the adult Bulbmin will eat juvenile Bulbmin following a leader.
 * The Pikmin appear to be orange, as hinted by the picture above, and by the orange coloration seen at the tip where the stem meets the leaf/bud/flower. If this is the case, they would be the only Pikmin type to have a separate idle glow/map icon color than their main coloration.
 * That being said, the orange coloration of the stem could be explained to be a translation of the orange gradient that separates the yellow front and the red back of the Bulbmin, or simply an arbitrary aesthetic choice to distinguish their stems from Red Pikmin.
 * Besides the size, adult Bulbmin and juvenile Bulbmin can be distinguished by the number of spots on their backs.
 * According to the Japanese version of Olimar's notes on the Bulbmin, the Pikmin attaches its limbs to the host's and secretes s. Additionally, it is mentioned that a recent theory suggests that it might be symbiotic rather than parasitic.
 * Although Bulbmin are not present in Pikmin 4, they are mentioned by Olimar to be Ambuloradicis akin to the Startle Spore.