Ball o' String Wario

From the Super Mario Wiki

Ball o' String Wario is one of Wario's many transformations in the Wario Land series. Getting covered in Wormy's spider silk in Wario Land 3 turns Wario into Ball o' String Wario, a rolling yellow yarn ball. Wario will roll back and forth across a course, bouncing off walls, until he eventually unravels back into Wario. In this state, Wario can break through some blocks. Also, this seems to be a combined ability of Snowman Wario and Flaming Wario.