A blue or purple who rolls with all the newbies and whites is probably just as prepared for the real world as a black belt who usually rolls with purple and up.
Expecting the unexpected is best learned from people who are the most likely to do the unexpected.
Well rounded fighter:
Physical fitness base. A significant strength and cardio advantage are the equivalent of years of skills training.
Muay Thai or boxing for standup.
A good wrestling base to defend takedowns.
Fundamental Judo to toss your opponent to the ground.
BJJ blue for the ground game.