shadowring

Hi, i saw your hack rom Pokemon mind crystal and found very cool. One feature that called my attention is that you made light ball work on raichu and pichu as well as pikachu. How did you do that? I'm still a begginer on hack rom so i don't know much, and i'm trying to make light ball useful to raichu in my pokemon fire red but i don't know how. i tryed to search every place but couldn't found any tutorial about items effects directly and how to change then. Could you explain to me how do i do this?  Thanks in advance.