Vex U and additional microprocessors

Vex U and additional microprocessors and sensors. I saw that Vex U teams have to run all sensors through the Cortex, but am confused if that would allow running some other microprocessor which then connected to the Cortex via I2C or UART?

Thank you for your thoughts.

VEXU you may run any additional electronics including other microprocessors. They may only be powered off of the cortex or an additional 9.6 of 7.2 V vex battery though. Any electronics to manipulate this battery voltage is also allowed.