One team is security; the other is black hat.
Each team has a mole. The mole cannot reveal their position...
Mutiple iterations.
* Develope/Secure a [type] of site against [type] attack
* Create/Find resource leach
* Create/Recover from, [outage type]
These teams should be sponsored by various vendors... A weighting system needs to be developed.
You'd want a balanced team; where you have a range of skills in your team; where you also have a need for their expertise in each step through resolution.
It would be even more interesting to develop the team that writes the scenarios...