This puzzle is a variant of U-Bahn, and it is named after a fighting duo in Paper Mario: The Thousand-Year Door.
If you are unfamiliar with U-Bahn, here is a guide that covers the core logic.
Draw two separate loop networks through the centers of some cells, which may not intersect each other. Each loop network may branch or turn, but may not have any dead ends.
Clues on the top and left apply to the first loop network, and clues on the bottom and right apply to the second loop network. A clue outside the grid indicates how many times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the corresponding row or column, irrespective of the line shape's rotation.