Mario has been accused of spreading ink across Delfino Isle. So his job is to clean it all up. What he doesn't know though is that another enemy- Baby Bowser, has disguised himself as Mario so that he would get accused.
FLUDD is a water tank that Mario uses to squirt at bosses and enemies. There are four different nozzles in his tank called squirt (normal), hover, rocket and turbo (booster).
Yoshi has been trapped inside of an egg, and the only way to free him is to give him the fruit that he needs, now once you do free him, you're able to ride him while he will help you.
The Piantas' home is located atop a large hill with an endless drop down, by the looks of it. It is called Pianta Village which is the last world you will ever encounter aside from Corona Mountain. The Piantas have trees on their heads as relief for the Sun's heat and a way to argue (whose tree is taller), but the Piantas hate swimming, even touching water, or getting splashed by it (also getting squirted by F.L.U.D.D.)! The whole world of Isle Delfino is inhabited mostly of Piantas, and which there is not a single world that has no Piantas, except for Noki Bay and Corona Mountain.
Nokis have a spectacular view of their ancestral home, the amazing Noki Bay, and plunging down to go to the underside of the sea, it is quite terrifying for some because of its large space and believe it or not, it is bottomless. The Nokis wear seashells on their head as a reminisce of their home. They have the ability to swim and survive underwater unlike Piantas which makes sense because the Nokis' home is surrounded by water. Jellyfish are also quite close friends of the Nokis.