From the Super Mario Wiki
Intelligent Systems is a video game company and subsidiary of Nintendo. They have created the Paper Mario series and have assisted in developing the WarioWare series, since WarioWare, Inc.: Mega Party Game$!.
They are also the producers of the Fire Emblem series, which was mentioned in Paper Mario: The Thousand-Year Door, and appeared starting with Super Smash Bros. Melee. They have also assisted in making the aforementioned, Super Smash Bros. Melee, Super Smash Bros. Brawl, and Super Smash Bros. for Nintendo 3DS / Wii U. Intelligent Systems has also helped Nintendo to debug the systems and to develop the Nintendo 3DS Camera application into the handheld system. In the staff credits for Mario & Luigi: Paper Jam, the company appears as special thanks.
Mario games developed