u can play with 0 stamina in normal match as far as i know
correct - but your players not gonna earn skills because they don't have condition to spend.
In friendlies it's a 0-3.

In officials
League :
If oppo doesn't have 11 eligible players, you win 3-0 without a game (but a latest issue is that it counts as a draw in season's stats).

CH.L. - S.L. - Cup :
If oppo doesn't have 11 eligible players, you win 3-0 in both home and away match and pass to the next round automatically after the first game.

If both teams don't have 11 eligible players, the game engine examines first the home team so give to this one the game penalty.