Software coding challenges. Written examinations.
Adopt technical training so that everyone is aware of, has a consensus of, and follows industry standards and best practices.
Results are conflated with quality such that no regard is placed on quality. Teamwork is conflated with attitude such that work with long-term benefits to the team is unrewarded.
The primary customer is so disappointed with the software that all contracts were cancelled and will never be renewed. Accept customer criticism - they are always right. Adopt technical training to improve software quality.