there are 4 shimigami arts:
Kidō (鬼道, Kidō? lit.demon path)
Hand-to-hand combat (白打, hakuda?, lit. white hits)
Agility (歩法, hohō?, lit. step method)
Swordsmanship (斬術, zanjutsu?, lit. cutting technique)
I imagine hollows normally dont have Kido and swordsmanship since you could relate "Sonido" as Agility and "Cero's" and "Bala's" as Kido. But when they tap into the hollow powers they can access this other arts and also aquire a boost in power for some reason.
And to be truthful I do believe there must be a few natural arrancars... most likely high lvl adjuchas or vastro lordes. Cause we know a shimigami can do it and become a vizard... so a very powerful and controled hollow like adjuchas and vastr lordes could achieve their tapping into the shimigami power. But I dont think their are a lot since their arent a lot of vastro lords.