Teamwork is essential GTFO. You need to make sure you talk to them before each race and make sure you are all on the same page. A key part of talking to them is figuring out what tools you plan to use during your run. Your team can have four members, but each of you can only use one tool.
The Biotracker. Before you and your team enter a room, you need to make sure that the door you are about to open does not lead to a large monster infestation. This is where the Biotracker comes in, giving you a clear idea of all the biological shapes on the other side of a wall. You can use this tool to plan your attack before you unlock a security door. Tag all enemies to watch them move around your neighborhood for a short time. The big gray dots are the sleeping enemies and the red ones are the scouts looking for your team.
Deployer of mines. If you're about to unlock a security door, you need to prepare for the issues. The door will make a lot of sounds, exposing you and your party to enemies until you disarm it. The person with the mine deployer can slap a few useful dangers that enemies will go through before they reach you. It won't free you from all the threats that are rushing at you, but it will save you time.
C-Foam Launcher. Aim this launcher on the ground to slow the enemy down, forcing them through a slime haze, making it easier for your teammates. But it doesn't last forever. If the enemy tries to force their way through the door, you can aim the launcher to plug all the holes, making it much harder for enemies to break it. You want to use the launcher immediately because it dissolves if it doesn't connect to a gate or enemy after a short time.
Le Sentry Gun. You have two versions of it: a close range shotgun variety and a medium range submachine. They both favor different tactics, so make sure you have the Sentry Rifle at a proper range. When he has a green light in front of him, he searches for enemies and is ready to shoot. When the light turns red, it detects an enemy and shoots them. If the light turns gray, it means that there is no more ammo, and you need to donate more before you can continue to protect your team.
When your C-Foam Launcher, Mine Deployer, or Sentry Gun runs out of ammo, you need to use the Tool Refill Pack to give them more uses.