It's dangerous to go alone, take this!
There are multiple ways player characters can help each other in Charge. They could assist each other, make a setup action, or even protect someone from danger.
When you assist, you help another player who's making an action roll. Describe what your character does to help. When doing this, you also expose yourself to possible danger.
Consume 1 momentum, and give them an additional 1d6 for their roll.
I can't reach it, can you give me a boost?
You step in to confront a consequence that one of your teammates would otherwise face. Describe how you intervene.
You can make a determination roll to try to reduce or cancel the consequence.
You suffer the consequence instead of them. You may call for a determination roll to reduce or cancel the consequence.
Get behind my shield!
When you perform a setup action, you make an action roll to have an indirect effect on an obstacle. If your action has its intended result, any member of the team who follows through on your maneuver either gets an improved effect or a reduced risk for their roll.
You choose the benefit, based on the nature of your setup action.
Make an action roll to improve the effect rating or reduce the risk of a future action roll.
First I'll distract them. Then you gotta make a run for it. OK?
This is a good way to contribute to an operation when you don't have a good rating in the action at hand. A clever setup action lets you help the team indirectly - either in the moment or via a flashback. Multiple follow-up actions may take advantage of your setup as long as it makes sense in the fiction.
From Zero to Limited
Since a setup action can increase the effect of follow-up actions, it's also useful when the team is facing very tough opposition.
Even if the PCs are reduced to zero effect due to disadvantages in a situation, the setup action provides a bonus that allows for limited effect.
This gives them a fighting chance.