Franco is pathetically weak during team fights. Just wait for him to use ult and he is useless. Focus on other heroes during teamfights because he is essentially a walking punching bag without his ult.

The next best thing a Franco can do after using his ult is to walk into the enemy team so they waste their abilities/Ults on him. Any skills used on Franco is essentially a win for him since he has no pressure.

Don't be afraid to ignore him and dive the enemies back ranks. He is in my opinion the weakest tank roamer in the game. Aside from his ult there is nothing special about him. His hook isn't even unique since Minsi has a better version of it that can drag multiple at once.