Brewology

Lets see... What should I use for an example? OH I KNOW!

SEGA Genesis can play SEGA Genesis games just by seeing "SEGA Genesis" ... (... near the top or something like that. I know just by hex editing) and SNES games can play SNES games just by seeing "SNES" somewhere. (Near the top once again by hex editing) Are you following? I hope you are. What if someone were to create a software that manipulates any other CD for another Console say XBOX or Playstation and thinks of it as a Wii game! Is it possible to create such a software for Homebrew Channel maybe?

Now I know it sounds stupid (and most likely IMPOSSIBLE) I am just asking a hypothetical question.

Actually, that's not how ROM's work or how game systems load games.
They don't find where it says SNES or SEGA, they just read the file that's in the cartridge and if they can read it, they run the code. Every console has a different way the codes are written.
Therefore, you'd have to edit a lot more, probably 99% of code to use a simple PlayStation game on the Wii.
That's why it's easier to create an emulator.

Oh I see.

Yea different games for the different systems have different files. Say the N64 can run .N64xkhag files and the PS1 can run PS1lhvcsa files.
The N64 games have the first file types and the PS1 games have the latter. Therefore the N64 can't run PS1lhvca files which are PS1 game files.