How to get Blue Pikmin
The main group of Pikmin in your aresenal will be offered to you throughout the campaign. There is no side mission or quest to complete to get the Red, Yellow, or Blue Pikmin. So before we collapse when you find out about them and add them to your team, if you're trying to avoid spoilers, you can stop reading now. All you have to do is push through the single player campaign and eventually you will find them. For those who want to rush towards this goal or just want to know when they will arrive, we will explain when you get the blue Pikmin in Pikmin 3 Deluxe.
The blue Pikmin are the last type you will discover in Pikmin 3 Deluxe. They can be found in the Garden of Hope scene, which unlocks once you complete Twilight River. Once there you will need to catch some Pink Flying Pikmin, as they are essential to get to the Blue Onion that distributes the Blue Pikmin. Once you have them, simply head to the right and through the opening to find a small body of water with the blue onion in the middle. Throw some flying Pikmin at the Onion and they'll dig it up and bring it back to the base. From there, you can create more Blue Pikmin whatever you want just by having your current party bring back items to breed.
What does Blue Pikmin do
Why do you want more Blue Pikmin? Well, I told you right near the top. These guys can't drown because they breathe underwater using special gills. Do you remember all those areas of the map that were filled with water? Remember how you couldn't take any of your Pikmin in there to get things? Blue Pikmin can walk in and underwater, so whenever you're looking in a lake or across a river, make sure your team is all blue and you're good to go. Unlike other species, this is their only bonus, so if you don't go in the water you can usually leave them behind.
This is how to get a blue Pikmin and what they do in Pikmin 3 Deluxe.