Lemures: the most jello-like of all incarnations of Law and Evil. I'm not sure if anyone ever uses those, as by the time PC's can travel to Baator they'll be pushovers.
A lemure's stats are bad. No bonuses of any kind, a -6 charisma penalty, and no intelligence. Even worse, where other creatures can typically easily gain intelligence with Awaken or one of its many variants, no such option exists for outsiders.
Lemures have two claw attacks that deal pathetic damage: you'd only have a reason to use them if your DM rules lemures can't use weapons. Sadly, this is something well within reason.
Do lemures have no redeeming qualities at all? They kind of do. Standard devil immunities aren't coming cheaper than this, and one could interpret Mindless as sticking around even after they gain an intelligence score. This'd make lemures a small package of defensive abilities that takes up two levels (plus whatever gets added on in the process of giving them intelligence). It's not a small trade-off for any build, but not completely unreasonable either.
+0 LA, which I hope everyone agrees with.