You want use Raspberry pi with cell phone as camera.
If you use cell phone, you have to turn off its wireless communication function (For example Bluetooth , Wifi,,, etc). In RoboCupJunior, wireless communication is permitted only between robots. Reference general rule:
You have to prove it any time when a judge or an interviewer request.
Then you will use cell phone as only camera with wired communication, there is NO PROBLEM.
Please post in correct category (RobnCupJunior Rescue Maze ) from your next question.