If you have that many people including carnivores and vegetarians/vegans, your best bet is Fire and Ice at the Garden Walk. You can make whatever you want, it's all you can eat, and they'll even cook something in the back for you if you have gluten allergies.
In Anaheim at the GardenWalk there is the Fire and Ice grill. We love it there. All u can eat and strong drinks https://fire-ice.com/locations/anaheim/