One of the signature features of hero shooters like Marvel Rivals is the ability to transform your team comps on the fly throughout a match.
This allows you to adapt according to your team's needs, to counter the enemy team, to the current position of the map, and so on.
In general you can mix and match the roles as need, but make sure to have at least 2 Strategists as there isn't a hero that can solo heal just yet.
In this guide, we'll cover different team comps and how they work so you can understand the right situations for each.