pkmnapi
cost to use?Nothing (for now). It is a free service.
I don't know. Or rather, I do, but I'm not telling. Please obtain Game Boy ROMs legally (i.e. a backup of your own physical copy).
See the Disclaimer section for more reasons why.
pkmnapi
to create a mod?Yes! That was one of the intended goals of this project. See the section on Changing Data for some concrete examples of how to create a mod.
Yes and no. Additional Pokémon may not be added, but Pokémon may be totally replaced (new name, new type, new pic). There must always be 151 Pokémon.
MissingNo.'s appearance in the game is due to a glitch and can appear differently depending what is currently in RAM. Since pkmnapi
only consumes the ROM, it is not currently a goal to allow access to MissingNo.
For some great background on the glitch, check out this video by Retro Game Mechanics Explained.
Feel free to open issues or pull requests on the GitHub repo.