Olivia can transform into enemies in Paper Mario: The Origami King
There's an interesting tidbit that was not featured in the Paper Mario: The Origami King trailer video posted by Nintendo of America.
If you go onto the official Japanese website for Paper Mario: The Origami King, there's a section that outlines the battle system, which they call the "360 degree battle" in Japanese.
The page mentions that Mario's partner Olivia, has the ability to transform into this giant turtle enemy, after it has been defeated. This giant turtle features the four elements: ground, water, fire and ice.
In the following video, after the initial battle, it depicts Olivia folding into the giant turtle, and using the turtle's abilities to take down this tall structure, perhaps using the "ground" element in this situation. Finally, using the turtle transformation in battle against other enemies.
It's not mentioned what other enemies that Olivia is able to "fold" into, but this new ability is quite interesting and leaves open lots of possibilities for the game. We should have plenty of surprises when Paper Mario: The Origami King is released on June 17.