The Team class is a very simple ScriptableObject containing a list of allied teams and an Editor-Only description:

public sealed class Team : ScriptableObject
    [Tooltip("Other teams are enemies by default unless they are in this list")]
    private Team[] _Allies;
    public ref Team[] Allies => ref _Allies;

    [SerializeField, TextArea]
    private string _EditorDescription;

This allows characters on opposing teams to hit each other while characters on the same or allied teams don't harm each other.

Enemies Allies

There are currently 3 teams and you can create more by Right Clicking in the Project window and using the Create -> Platformer Game Kit -> Team function.

Player Green Brown
The Player Gobblers All other monsters