There are quite a few on the market i just wanted to know if any are legal.

in the rules you can find this: ¤ All variants of VBA are banned from all GB/GBC games. Approved emulators are Gambatte and BGB. ¤ If using emulator, using save states and speedup for any reason (including reaching the New Game screen faster) is not allowed. ¤ Using emulator to create custom palettes that are not usable on any kind of official console is also banned.

i assume that the approved emulators are the only one allowed.