The main difference between the Régiment de Cuisine and a regular Shokugeki is in the format of the challenge; rather than a single cooking duel between two parties, a Régiment de Cuisine consists of multiple battles.
Teams are generally equal in number, however, there have been instances of opposing factions having different member counts. Jōichirō Saiba, for example, single-handedly took on a team of 50 3rd year students in his 2nd year and won by himself.
In each round, a set number of members from each team face off against each other in simultaneous 1-on-1 duels. Teams are allowed to choose who battles in each round. Additionally, team members are allowed to assist in their teammates' cooking during the battle.
If a team member loses their duel, they are permanently removed from the group and cannot face in any subsequent battles. Alternatively, a team member who wins will stay in the competition and can then compete in a later round. Once one side has lost all of their members, the opposing side wins the Régiment de Cuisine.
Stipulations and conditions to set up a Régiment de Cuisine are the exact same as a Shokugeki, and like a Shokugeki, a Régiment de Cuisine is meant to solve a dispute on campus and can be initiated by anyone.