[Other] Every Time I open my fire red hack i get a black screen.

[Absoldoom]

Every time I load my fire red hack I made whenever I press enter I get a black screen. It started doing this after I changed Charizard to a Rapidash what do I do ?!?!?!?! And Also how do I add more starters

 

[Mana1]

You probably broke something, the easiest fix would be to start again.

You add more starters by writing new scripts and editing the existing ones to include more options. It's not a simple edit, it'll take a fair bit of time.

 

[Lance32497]

If you opened A-Map, compare the .bak file created by A-map to the bugged rom, then find the byte in bugged that isn't similar to the bak file, try to do manual hex edit or think if that byte is the byte you had changed, if that's the byte you had changed then try to put the bytes and address on notepad for a back-up then try to edit those bytes, see if it fixes the problem.
about the starter
the simplest way of giving starter
is the givepokemon command then followed by setflag 0x828 but that's very simple, if you want to make it more cool, read Scripting tutorials or take a look on Scripting thread.

 

[Anexenaumoon]

Do what Mana or Lance said, or just get a new ROM honestly

 

[Criminon]

You can also get a hex editor that compares data. Remember to always back up files. Use your most recent back up and pop it into a hex editor and compare the file with your broken one and see whats different, and try changing it back. Trial and error.