QuoteThen these plugins would transfer to a game that uses them?
No, editor plugins (COM plugins I think they are called) are different from regular plugins in that they affect the editor only. They can be used to simplify tasks, but they don't affect the game as such.
You could, for example, write a path editor, that automatically generates a series of MoveCharacterPath commands just by clicking in the room editor.
The only editor plugin I'm aware of is the Media manager, though I doubt it works with recent versions of AGS.
I think a combat system would be more suitable for a regular plugin or a script module (just introduced in AGS v2.7 Beta 13).
The COM plugin API is explained here.