The question came up on one of the forums I frequent on how to use an entire team of villains during play, which isn't all that well covered by the normal action scene design rules due to your limited budget of scene elements. The following are examples of how I've approached the subject:
- The easiest approach if you just want to do a big brawl between two teams would be to downgrade some or even all of the villains to lieutenant stats, building them so their traits loosely reflect their normal full-villain abilities. For a moderate scene with H=4 you could take two pairs of d10 lieutenants as two moderate scene elements, a full villain (the team leader or heavyweight) as a moderate element (or difficult, if upgraded), and then use your fourth element for a moderate environment, or perhaps split the slot into an easy environment (ie somewhat hero-friendly) and an easy d8 lieutenant (the team chump or toady). You could also shuffle things around to squeeze in some initial challenges or minions, but this might be complex enough as-is.
- You could also do the trope where the heroes encounter smaller groups of full villains (say 2-3 at a time) who are focused on doing the set-up work for their team's grand scheme, with them fleeing as soon as their goal is accomplished, possibly leaving a prisoner behind to be interrogated. Repeat that two-three times with minor variations and montage and/or social scenes between, then (probably next session) have a grand finale where the heroes confront all the remaining villains. You can turn the difficulty dial up or down as needed, adding minions, challenges or even a heretofore unseen villain to the villain side if needed or using a more hero-friendly environment and/or NPC allies if the heroes are are outnumbered by the remaining villains. You really don't need to be precise about counting the scene elements here, and you could just grant bonuses or penalties for impromptu tweaks based on earlier scenes, eg a villain who just barely escaped defeat by a specific hero might suffer a penalty the first time they act directly against them, or the heroes might have a team pool of bonuses earned from social scenes interrogating defeated villains.
- The flip side of that trope is to have both teams confront one another early on in an unbalanced scene where the heroes are at a disadvantage, letting the dice fall where they may. If the PCs lose or time-out, they're defeated and wake up in captivity with a free zone heal or two each, and then play out a montage scene to free themselves. Any heroes who weren't defeated (presumably through some Overcome that involved escaping the fight and then stealthily following the villains) will, of course, find the prisoners just in time to help. From there they can gather info, sabotage the villain lair, and/or ambush unprepared villains before the inevitable big rematch as the remaining baddies are trying to execute their scheme. This is a classic comic arc, but don't use it if you aren't 100% sure your players will buy into it. A lot roleplayers absolutely hate losing a fight no matter what despite Sentinels making it a largely painless experience. OTOH, if they are 100% into it, you could just shorten or even skip the initial big fight and just start with waking up captive as you collaboratively narrate their off-page defeat. Any group like that deserves a few bonuses for playing along with style.
- Another way to use a lot of villains in the same scene is to either drip-feed them into the scene slowly, eg of six villains, maybe only a couple start in play, then two more show up with some flunkies when the scene tracker goes to Yellow, and then the last two when it hits Red or when some arbitrary number of villains are defeated. You can also play around with mutually-hostile villains who act against one another when they see an opening and aren't being pressed by the PCs. Be careful with this though, there's nothing players hate as much as watching NPCs roll dice against one another. Sometimes a bit of GM fiat is fine - but let a PC land the finishing blow.
