Friendship



Friendship is a game mechanic in, where every Pikmin has its own friendship level. Friendship is shown in the form of hearts. Doing various actions with a Pikmin fills a small portion of a heart. The lowest possible friendship is 0 filled hearts, and getting a Pikmin to 4 filled hearts is a way to get Decor Pikmin. From there, a Pikmin's friendship can be increased further, with the red in the hearts being replaced by gold, up to a maximum of 4 golden hearts.

Raising friendship
A Pikmin's friendship level can be increased by feeding it nectar in the garden screen, sending it on an expedition, or sending it on a mushroom battle.

A red heart of friendship requires 53 points of friendship to fill, so reaching 4 red hearts requires a total of 212 friendship points (To note is that the first, second, and last points of friendship gain within one heart do not visibly change its appearance, while the rest do). Golden hearts require 4 times as many points of friendship to fill, meaning 212 points in total are needed to fill one golden heart, or 848 points in total to fill all 4 golden hearts. The friendship points gained from various actions are as follows:
 * Feeding nectar to a Pikmin gives 1 friendship point.
 * When a Pikmin has had 4 petals plucked from it, feeding it nectar will give a bonus 10 friendship points on top of the 1 it would usually get.
 * Feeding special nectar to a Pikmin gives 53 friendship points, equivalent to one full red heart, or one quarter of a golden heart. (Note: The 10 bonus friendship points do not apply when special nectar is fed after 4 petals plucked)
 * Sending a Pikmin on an expedition gives 1 friendship point.
 * Sending a Pikmin on a mushroom battle gives 3 friendship points.

Pikmin visibly gain friendship after being fed nectar, if they immediately return to the active squad after their expedition reward has been collected, and after the score of a mushroom battle is displayed; this is shown by a heart briefly appearing above the Pikmin's head. Note that Pikmin returning to standby after an expedition will still gain friendship, even if the heart animation doesn't occur. If friendship gain is enough to fill the current heart, the heart will persist for longer and expand with a special sound effect.

Strategy


The 10-point friendship boost for feeding a Pikmin nectar while it has 4 out of 6 petals plucked is the biggest friendship boost for any action that doesn't include the rare special nectar. It fills nearly one-fifth of a red heart, so prioritizing this when feeding Pikmin is important to raising friendship quickly. A Pikmin will visibly hesitate before taking the nectar on the fifth feeding, which is how you can tell you're up to it. Doing this uses a lot of nectar for a large squad, so it can only be done occasionally; it is recommended to do it when nectar numbers are higher and petal numbers are lower, and to save fruit expeditions until after doing it.

The most nectar-efficient way to do this strategy is to feed a Pikmin 5 nectar in a row, making sure the first is not white nectar if the Pikmin starts with a leaf, and also ensuring the final flower is left unplucked. After this fifth feeding is complete, waiting two hours will cause the "Petals Plucked" count to reset. Plucking the fifth flower from the previous feeding after this reset occurs will take the current count up to 1/6. This reduces the number of feedings required to again achieve the 10 point bonus for feeding after 4/6 petals plucked.

Effects of friendship
When a Pikmin that didn't come from a Huge or Golden Seedling reaches a friendship level of 4 hearts, a new expedition for a gift box will appear. The Pikmin that reached 4 hearts can be sent on this expedition, and upon getting back to the player, will turn into a Decor Pikmin.

Pikmin with a higher friendship level are stronger in mushroom battles. The number of completed hearts a Pikmin has is used in the formula to calculate its attack power.

History
The following changes have been made to friendship over time: