Originally Posted by Buruma
I've been looking for a decent online co-op game to start soon and I am considering this title. I only have one real concern while browsing the achievements, though. Is it possible to get 100% in one playthrough if you are sharing every challenge, mission, etc... with a co-op partner who needs everything, as well?
I'm not sure about that sorry, maybe someone who did this should answer this since I did it all solo.
To make things sure you and your partner should go for the very first achievement like Dead Presidents
(takes roughly ten minutes), Shake and Bake
(pick an easy one) and see if it unlocks for both then you will know it.