"Vanligvis" is an adverb while "pleier" is a verb. You can use them to convey the same idea but you need to construct the sentences differently.
Hunden vår er vanligvis vennlig - Our dog is usually friendly
Hunden vår pleier å være vennlig - Our dog tends to be friendly
I guess one could argue that these sentences are not identical in meaning, but I personally think they're interchangeable.