crocodile attacking a player from the water, is that an attack roll followed by a grapple check? grapple is automatic, no check, with hit

— Mike Mearls (@mikemearls) July 10, 2017

used living rugs to grapple PCs so an illithid could eat them then felt guilty and made illithids grapple also. Which was correct?
ability specifies mind flayer must grapple target, so you are correct to have them also grapple

— Mike Mearls (@mikemearls) July 10, 2017