The "Fighters who take part" part is problematic. What it means RAW depends on how "take part" is defined RAW - is it getting on the table, or is being part of a participating gang sufficient. In NCE I feel we're currently gravitating towards the former, and the term isn't originally defined.
I'm thinking of treating the sentence part as something like "Gangs who take part". This would fit the way our group plays it.

Now the "participating gang"... It would mean one of the two gangs originally involved in a fight, plus any others coming along in multiplayer scenarios. The detail that experience actually goes to the fighters and not the gang is covered in the specific points, and it's either restricted to participants or not.
That could theoretically allow a gang to participate without any fighters making it to the table. It's possible, e.g. with proper Serious Injuries.

Now I don't think there's a way for such a gang to actually win... no, that depends on the scenario. Caravan could work. Hilarious. Should the winning

Leader get an award in such a case?
Now that I think about it, loosely on topic - Old Battle Wounds and the Leader. The scenario is chosen before OBWs are rolled. Let's go with The Hit. There's nothing RAW that would help if the target leader went OBW, is there? Actually, it's somewhat close to an instant win for either side, as the defending gang leader is treated similarly to Out Of Action, but will not ever go Out Of Action during the game. Would get dumb if the Leader had an Infected Wound. Easily hotfixed by dragging the leader out anyway but it does need fixing, even if on the spot.