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!
Bride to be in 2015, Malay Mixed Marriage Johor Bahru