I don't have a color chart in front of me, but it's not going to be a question of dark enough. The real question is, "will the green dye, combined with the purple plastic give me green, or black?"
If you use the hunter green (dark) green, it will certainly cover up that light purple, but there's no guarantee that it will give you the color that you are looking for. Also if you do try it, the thin plastic on 25th figures warps in even moderate heat, so be very careful and keep your temperatures low.
Or you could always wait for the inevitable repaint of the mold to be released.
- R
If you use the hunter green (dark) green, it will certainly cover up that light purple, but there's no guarantee that it will give you the color that you are looking for. Also if you do try it, the thin plastic on 25th figures warps in even moderate heat, so be very careful and keep your temperatures low.
Or you could always wait for the inevitable repaint of the mold to be released.
- R