People starting Pikmin Bloom for the first time might experience a connection issue depending on whether you use a Google or Nintendo account to log in. Both the official support page and initial reports note that starting with a Nintendo Account blocks you from using other logins.
Here’s how the problem goes. When someone begins playing, you choose which account you might want to log into the game with. The problem arises if someone chooses a Nintendo account. Should someone use a Nintendo Account to log in and play Pikmin Bloom, then they can’t later use say a Google account or account from another Niantic game to log into it. This means if the other account you wish to link is tied to perhaps Pokemon GO, the game will claim your account already exists and not allow it. If someone uses any other account for the initial login, this won’t happen.
As for why someone would want to link a Nintendo Account to Pikmin Bloom, there are exclusive benefits. To start, someone’s Mii will appear as their in-game avatar. They will also get a Special Seedling. Once it grows, you’ll get a Pikmin wearing Mario’s hat.
Pikmin Bloom is available for Android and Apple iOS devices.