Hey guys, i what to learn how to fully hack a Pokemon ROM, and i don't just mean little things like changing the starting pokemon on it but learn how to fully code it. I already have a great amount of html coding experience and i'm a fast learner when it comes to coding things like that. I thought it would be a cool skill to have to be able to code a pokemon rom. The way i see it, some people who make their own rendition of a rom must be learning it from somewhere, i just wanted to know where they get the info from if it exists or are they personally thought these things from a tutor or something. I just thought i'd ask before i land myself in a dead end, thanks in advance for any advice.
oh and another thing, i hear from different angles that "it's legal" or "it's illegal", care to explain before i put myself in a bit of trouble.