Have a small number of roles to choose from, and a token that lets you change your role.
Each role boosts a piece type?
Pawns can move diagonally without capturing.
Bishop can move one space orthogonally.
Rook can move one space diagonally.
King can move like a knight.
Knight can move like a king.
Simpler option: allow a king's move for any piece type? Probably exclude king and queen.
Token starts in the middle. At the end of your turn, you may take a role if the token is in the middle or on your side. Return your old role if you had one.
Allow stealing your opponent's role? If so, opponent gets a free role choice immediately, and keeps the token. Getting new role at start of turn enough compensation?
Have a small number of roles to choose from, and a token that lets you change your role. Each role boosts a piece type?
Simpler option: allow a king's move for any piece type? Probably exclude king and queen.
Token starts in the middle. At the end of your turn, you may take a role if the token is in the middle or on your side. Return your old role if you had one. Allow stealing your opponent's role? If so, opponent gets a free role choice immediately, and keeps the token. Getting new role at start of turn enough compensation?