I tend to agree with Kevin that the concept of "recommended cores" is too rigid and unflexible-- the best cores are customized for a team.
I think the concept of rigid recommended cores is even worse when talking about stall, where the entire team functions like one defensive core (with all 6 Pokemon working together to deal with the many threats of the metagame). The concept of defensive cores works better on a bulky offensive/mixed team, where you are depending on only 2-3 Pokemon's synergy to take the majority of hits. It's different when you have dedicated stall with 6 defensive Pokemon working together.
Basically, I think recommended partners is better... :x