Hopefully you guys can help me out on this....For some reason i didn't get the secret mission 3 achievement while fighting Gattuso

I switched the diffuculty to easy mode..Was that the problem?..That i switched to easy mode while fighting the boss?.. the Reason i didn't get the achievement?...Any help will be helpful thankx!!

Anyone? please i need help!!!

First, let me say that damn your signiture is awesome. Second...

Get Gattuso as close as possible to the billybally plants, and lock onto the plant and try to hit it a few times. I'm not exactly sure how many times it takes the da** plant to spray on him to get the achievement, but I hit him with its pollen about 4 times before I got the "Great!" on screen. Try to hit in from a distance while hes close to it, or you'll get hit too. Either way though, stunning him with the pollen should do the trick.

Im already past that part already,But once i finish the game can i go back to get the achievement again?

Thats what I'm doing. I'm on my second playthrough, and getting the secret missions as I go.