We use the same roster size as ML teams - 25.
9 offensive starters
9 pitching spots
7 bench spots
Of course, you could bench ALL of your players if you chose to, so I guess we have 25 bench spots.
"The game has a cleanness. If you do a good job, the numbers say so. You don't have to ask anyone or play politics. You don't have to wait for the reviews." - Sandy Koufax