Depends on where you see them being mapped on the 3.5 nastiness scale.
In Ari's Iconic Bestiary: Classics of Fantasy (but here), he re-imagines Slaadi as creatures of choas that have randomized animal appearances.
Portals & Planes has a choas template that could be added to anything, though the changes are pretty small in scope (though one ability they get is pretty nasty.)