Well given the story overlap and the meet ups they created one wouldn't need to clear all Four to get major spoilers for each set of characters.
Good point. Though to be honest I've seen a completely different batch of "spoilers" which are hilariously the complete opposite of the one's Dusk just posted. Potential major spoilers, obviously:
Chris dies protecting jake
Sherry can die depending on your actions
Carla kills Ada
Leon and Ada kiss again as Ada dies in Leons arms again
Derek Simmons is final boss
All 6 players play together for final boss
Sherry can die depending on your actions
Carla kills Ada
Leon and Ada kiss again as Ada dies in Leons arms again
Derek Simmons is final boss
All 6 players play together for final boss