Exactly what do you mean by "make cartridges"? There are two parts really, making the game or application that goes on the cartridge, and making the cartridge itself.
When it comes to the cartridge itself, it's a question of scale. If you only want one or two cartridges, you are better off just buying a pre-existing flash cart and loading whatever you want on it. If you actually want to mass produce it at scale, that's kind of out of my area of expertises.
With a large enough scale I guess you could order actual mask roms, you would still need a mapper IC (unless you can fit everything in 32kb). Creating the case would require large setup costs, to create tooling for injection moulding.
At a medium scale, you might be better off buying old games to steal the case and mapper IC, putting in your own PBC and pre-programmed flash chip.
As for the software itself, that's several comments worth of information, but pandoc covers a lot of it. Development is usually done in an emulator for fast turnaround times and easy debugging, but you are to be careful about the accuracy of the emulator. It's possible to create games which work on some emulators and not the real hardware.
(I don't have the ROM to check in its case, but: just because it's a GBC game doesn't mean it runs in double-speed mode/requires the MBC5. Double-speed mode uses more battery life so unless it's necessary I'd hope the devs wouldn't use it...
at any rate, you should use whatever MBC the header tells you to use. Look at address 147h in the ROM and cross-reference to the list in the pandocs)
Your phone is probably not powerful enough to emulate a PS2 game either. As far as I know PCSX2 is not easily ported to other systems. You are probably have to wait a pretty long time to see PS2 emulation on a phone.
A quick google reveals this project: http://purei.org/ Havent checked it out.
Long story short, invest more time in research and less time in writing lengthy posts and making stuff up on the spot.
According to https://redream.io/help, it requires:
I believe this page has everything you want to know:
http://famitracker.com/wiki/index.php?title=Sound_hardware
And Famitracker is used a lot these days to make NES music:
Ok I just had this discussion with my friend at work, if you want the best emulation and homebrew your best option is something android based. Check out the Android handhelds on Amazon, specially the gpd xd plus but any cheap android device will probably emulate and do homebrew better than any portable Sony or Nintendo console.
https://www.amazon.com/GPD-Foldable-Handheld-Touchscreen-Hexa-core/dp/B01N9IG6BL
There's loads of portable Android based consoles coming out of China on Amazon that you can find YouTube reviews for
N64 and Playstation emulation has been flawless on android for years and there's dozens of emulators for each of the older consoles with any kind of feature you'd ever want. I think most of the Android handhelds are cheaper than new 3ds xls. I've been out of the emulation game for a while, not sure if there's good ps2 emulation yet, but ds emulation on Android has been great for a while also.
They can have wifi and Bluetooth support for wireless controllers and of course since it's android, you can download whatever phone app on the play store and use it to watch movies, YouTube, torrent files, IRC chat rooms, better browsers and everything. Sky's the limit on an android device.
Loads of android games on the play store also