VisualBoyAdvance for Mac is a game emulator that can emulate all the games that were available on the Nintendo handheld consoles, and is capable of supporting 1487 kb flash. The application also applies automatic IP patches to the games.
The GameBoy and GameBoy Advance emulations provided by this application are pretty accurate for an emulated environment.
VisualBoyAdvance for Mac is very easy to install and uses only a couple of MB of space. It works quite well on old systems, but it has been known to crash upon being installed in new systems.
There may be some display errors and you could find that it may not fit the screen correctly. That being said, it is one of the most comprehensive applications that support the old GameBoy environment.
Although VisualBoyAdvance for Mac is not a very complicated application, but novice users would need to learn emulation and its basics before beginning.