Mondai

and his partner Potcha were two imposters who tried infiltrating Konoha.

Guy and Lee Impersonator Arc
Mondai and Potcha went to infiltrate Konoha and gather its secrets by disguising themselves as Might Guy and Rock Lee respectively, while the real Guy and Lee were out on a mission. They are oblivious to the fact that their disguises are fooling nobody, except for Naruto. Tsunade, Sakura, and Tenten forced them along by giving them outrageous missions, preventing them from learning anything. They were defeated when the real Guy and Lee attacked them with their Double Dynamic Entry technique.

Trivia

 * Mondai calls himself while disguised as Might Guy, which is a pun for  which means "no problem".