ROM Hack Few questions about headers

[Eikonoklasm]

Hi, could I get my own header from any original cartridge that I currently have or is there a specific game to get a working header? Can I use these self-obtained headers on any game to play online? Thank you in advance. I know how to use headers but I'm not sure which one I should use.

 

[Lucifer666]

IMHO use a header from a game that doesn't have online

like Super Mario 3D Land

as far as anyone's aware headers work cross-game, you just don't want a lot of people using the same header at once that's it

 

[jimskeet2002]

I really believe the "safest" way is to use a private header from an online able game.

 

[Eikonoklasm]

Thanks so much, guys.