This guide will tell you how to get the “Outsider Baseball” achievement.
How to Obtain Outsider Baseball Achievement
How to Get the Achievement
To get the achievement you have to do the Darksider path / the “bad path”.
Then, When you get the Rhode fight you have to defeat her without getting hit.
If you get hit close the game and reopen it, you will spawn in the boss room.
If you get hit and continue the fight, when you finish the game will trigger an auto-save and you will have to reset all your progress and do the path from the start.
Hope this helps!