I would look into using Automator. For example, you could create a Service that is accessible from the Application menu (e.g. Mail > Services) that does what you want.
Speaking of Services, there's actually already one available for Mail that does part of what you want. More specifically:
- In Mail, select an email
- Then go to Mail > Services > New Email With Selection
- A new email window opens with the contents of the email you selected already in the body of the message (however, there is no subject line and the message is not formatted as though you're forwarding it)
Also, with regards to Team A and Team B, if you haven't already you can create a Group in the Contacts app for each of your teams. That way you can forward the email to the group.
You could look at using AppleScript, but in this case Automator is probably the best/easiest option. There are many online resources that can help you get started. Below are three of them:
Finally, feel free to come back here and ask questions if/when you get stuck.