A stalemate is when you are not in check, but have no legal moves. The easiest way to do this is online with a partner, but it can be done against the AI as well. Either way, you want to eliminate the enemies pieces except for their king and a pawn. Position your king in the last rank before the enemy pawn would be promoted, blocking his movement. Sacrifice your remaining pieces, keeping only two rooks and/or queens. Use your remaining pieces to shepherd the enemy king toward his pawn, and then sacrifice them such that your last piece is captured in the sixth rank, directly behind the pawn. The three last pieces on the board should all be in a column, with your king unable to move and thus ending the game in a stalemate.