Best tip for tankmates with lions, is to avoid other fish with teeth. Triggers and Puffers mostly, I would also lump large wrasses (who definitely have teeth) into that category as well. The others is to avoid are known 'bullies' with lions, such as aggressive angels like Passers and Queens, and Sohal Tangs.
Some great options for Lions include, large hamlets, large porkfish/grunts, snappers (you will need a big tank tho), passive tangs like Nasos (again, big tank), lookdowns and other jacks (huge tank), large angels introduced after the lion, and batfish (huge tank).