You have to breed it with the Turwig family in order for it to learn both attacks.
Leech Seed can be done with a male bulbasaur/Ivysaur/Venusaur and a F. Treecko.
Crunch can be done with M. Larvitar and a F. Treecko
UMM...did you not read my post?
What part of that is not understandable :P ?
All you do is breed the treecko with leech seed with a M. larvitar to get a treecko with leech seed AND crunch
You said the GBA games which was your belief of what the user has. So who knows. But that's the only possible way to have both attacks breed.Which, unfortunately, is inexistant in the 3rd generation. Which is what the thread maker is probably using, since he posted in the 3rd gen forum.