ROM Hack Hacking Types in Pokémon Black/White

[Ziggy Zigzagoon]

I honestly have heard little of this topic. I wonder what would be the mechanics involved making a new type. I know that I would even have to change references to the 17 types and make a new Arceus forme if I add a 18th type. I am more interested in the technical aspects.

 

[Slyakin]

It would be rather hard to; You would, like you said, be altering a core aspect of the game which can in-turn break a lot of stuff.

I don't think it has been done for any Pokemon game before (In the Brown/Prism games, I think they just altered the names and resistances/weaknesses).