A Pikmin that consists of two small Pikmin sharing the same stem. It will be able to sprout other Pikmin on its stem by drinking nectar but in turn, they cannot grow buds or flowers. This will make it count as multiple Pikmin in several tasks such as battling (A Twin Pikmin with 4 siblings counts as 5 pikmin attacking) or carrying (A standard Twin Pikmin will always count as 2 carriers). The more Siblings a Twin Pikmin has, the slower it will be. When it gets eaten, only several of the siblings get eaten and at least one of them survives(similar to the Ice Climbers in Smash Bros.), giving you a chance to find nectar and sprout new siblings again.
I have always wanted weather to have some kind of effect in the Pikmin games. Rain would make more aquatic enemies appear in an area that day and fill up small crevasses with puddles. Sunny days would make more persistent or fire-based creatures appear and lessen the amount of water in a level or something like that.
The Perilous Platea is an area which uses that idea and takes it further: It is based on the towering Tepui plateaus in South America, these plateaus are so high that the clouds have to traverse their steep cliffs, lie on the flat top of the tepui and lower themselves back the other side. Because of that, the weather on tepuis are very unpredictable, this area could be just as unpredictable by making the weather change during the day, thereby making enemies change their locations, among other things.