MrSin |
Scorpion style isn't a style like the other style feats. Its not a style you adapt to and gain abilities, its a feat that allows you to use a special ability(as a standard action, with an unarmed strike). If you want to take style feats as bonus feats without prereqs, you have to be a Master of Many Styles.
Kazaan |
As far as Scorpion Style goes, it's typically better to bypass it entirely since Monk bonus feats allow you to disregard prereqs and just get Medusa when you get to it since you can apply the needed status effect using Stunning Fist and Medusa can be used as part of Flurry whereas Scorpion and the second one in the chain can only be performed as standard Attack actions.