The fake Pokemon Gameboy games were all hacked versions of existing games if I'm not mistaken. A game built from the ground up on the other hand wouldn't have copyright issues, unless of course, people put copyrighted stuff in there such as actual pokemon. As for adding more types, that's my idea for balancing the type chart. Grass, for example, is considered underpowered, but by adding Light (which on my type chart, Grass is strong against) it would be made stronger.