In US English, an organization is construed as a single entity, so we use the third-person singular verb, is.
The name of the organization could be written as Villains’ Union, although not using the apostrophe seems more common; Villains Union means a union of villains, rather than a union that belongs to villains. Either way, Villains needs to be capitalized if you’re going to capitalize Union, indicating that this is the actual name of the organization.
Change the colon after strike to either a period or a semicolon.
Add a comma after jobs. Without the comma, the sentence is saying that the jobs themselves are compensating for the lack of people to save, whereas adding a comma makes it say the heroes need jobs because there aren’t enough people to save. (Honestly, the sentence could have been worded better, and then we wouldn’t have to worry if the meaning was clear or not.)
The Villains Union is on strike. Heroes are forced to find jobs, to compensate for the lack of people to save.