A race shifter in Ben 10

mc is sent to Ben 10 is sent with a system that allows him to tranform into a werewolf, vampire, demon,dragon etc. he's allowed to pick the race from their world like for example a werewolf from noblesse and a vampire from Hellsing or a demon from nanastu no taizai . mc will have at least 12 transformation because we don't want him being able to beat everbody without already some problems that just makes boring. note mc is only allowed the powers from that races note a shop for everything in the omnivere . pariring s could be Gwen , charmcaster or fem Ben no harem.