Empty. Again.

Monochrome Chess*

Sentinelles**

Add a (black or white) piece (not a Knight, of course, nor a Pawn, nor a King), then Black or White stalemates itself in one move.

Four solutions

(IMO, the solutions are obvious, but I could not verify them, so... amaze me!)

* Each unit may play to squares which are the same colour as its square of origin.

** On moving, a piece leaves behind a Pawn of its own colour on its departure square. The rule does not apply to Pawns, or to pieces moving from the 1st or 8th rank, nor does it apply if there are eight Pawns of that colour already on the board.