What martial arts are used in UFC?

You can use a number of styles in UFC, really almost anything goes. Ill advise Muay Thai which is Kick boxing with elbows and knees and some form of Wrestling or Judo.

Brazilian Jujitsu is very common allso. In my opinion if you don't have some Brazilian jujitsu under your belt you will be taken advantage over.

Another few are wrestling which is mostly takedowns. Boxing is used a lot also. NOGI jiu jitsu. Judo is takedowns as well