The Ninjalinos are very obedient towards Night Ninja's orders. They don't speak in the English language and instead mumble, sing, or laugh. They will also follow in Night Ninja's emotions such as the time he nearly cried in "Owlette's Two Wrongs" because his statue was ruined by Owlette. In "Owlette and the Owletteenies", they finally grew sick of Night Ninja's constant demands and criticism and decided to join Owlette. For that episode they were deemed her "Owletteenies". They eventually became disobedient towards her and went back to Night Ninja's service.
The Ninjalinos all wear fully-covered ninja costumes, similar to Night Ninja's. However, their outfits are a dark purple color as opposed to Night Ninja's dark blue. They have purple eyes.