Your first concern should be that Leafgreen isn't technically part of Kanto Generation (Color Generation). I'll not try to mod (and if I did, I apologize...).
As for your problem, I'm not sure. Check the guide if you have any questions. The one main thing I've found about this site is that their guides are very accurate and incredibly in-depth. I'm sure you can find your answer by looking at it.
Hope this helps!
It's great to complete a Pokedex! So I'll need some help...
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