OP said Genesis games guys =P
Generally, Genesis games were programmed in 68000 assembly (although some games used a mix of assembly and C, like Ecco). In earlier Genesis games, the Z80 only handled sound samples through the DAC, while the 68k handled the FM synth. Later games used the Z80 for both FM and DAC.
There are several dumpers floating around that can handle Genesis games, but many of the oldschool grey market copiers can be a bit hard to find (for example, I just bought a 16Mbit Super Magic Drive, and I'd been looking for one for about four years now). Examples of Genesis-capable dumpers include Super Magic Drive, Multi Game Hunter (which I hear is shit), Multi Game Doctor, Double Pro Fighter, and others. There is also a
dumping method that connects a cable between the PC parallel port and controller port 2. It requires a Sega CD and custom software burned to CD. This method can dump all licensed carts, even Super Street Fighter II (which is 40Mbit, and uses bankswitching, due to the fact that the Genesis can only see 32Mbit of ROM without banking). It can also dump SMS carts as an aside, you must have an SMS adaptor with pin B30 taped over or disconnected.
They're a bit expensive, but
Tototek has 32Mbit and 64Mbit flash carts (the 64Mbit one can support SSF2, as well as 32X games if you have a 32X). They're a bit expensive to use as distribution carts, but they should be handy for running ROMs and testing your own homebrew code.