Hi ColorMePretty, for gown, there's one called Belle Couture. (http://bellecouture.com.my/)

For makeup in Johor, there's two listed here (http://recomn.com/businesses/search?utf8=%E2%9C%93&query=Makeup+Artist&locations=Johor)

Someone here also mentioned Andy Lim for photographer. He really has a lot of references from his ex-customers (you can see if you visit the site above and search for photographer), so should be a good choice.

Hope this helps!