I didn't know this thread existed! I was looking in the Creative Corner. Anyways here are some I've come up with:

Title IX
Rules: You must field an equal number of men and women on your team. (Slightly easier to build strategies for than the "All Women" scenario).

Bumper Cars
Knockback and Knockback Damage cannot be ignored. All damage from attacks is ignored and instead applied as knockback. Critical Fails just mean the character knocks themselves back. Maps should probably be limited to those without mostly open space. Maps with "fall" and "lava" terrain are great for this. For consideration: 1. objects placed act as blocking terrain, 2. Characters do not halt knock back, but are also knocked back as well, or 3. Characters count as blocking terrain for knockback.
You might need to score on individual damage instead of points through KO's. The game could potentially take a LONG time.

Epic Fail
All hits are misses, and misses are hits. Should limit this to Modern Age.

Running with Scissors
Each player places an additional Ultra-Light Object, "Scissors", on the map. This object cannot be destroyed and may only be picked up or moved by the team that placed it. When a character carrying the "Scissors" object ends a move action, it may be given a close combat action as a free action to use Blades/Claws/Fangs targeting each character it moved next to during the move action. The result of the Blades/Claws/Fangs roll is a max of 4.
Edit: I guess you can throw the scissors as a sort of ranged B/C/F, I just hadn't thought of that until now.

An evil scenario I was thinking of doing was the classic "Build a team and make your opponent play it". However, when everyone shows up with their uber-cruddy teams, you make them play the team they brought. I haven't tried it, but when I do, I genuinely hope I get to see the look on the guy's face who brought the team with all 0's in their damage slot.

Now bare with me on this one as it is untested and simply running through my head.

It's based off of the Secret Invasion arc but you don't have or use Skrulls for the game effect and direction. I'm also trying to devise more co-op game scenarios...

It's designed to start as a vs but should turn into a co-op. I'm gonna use Skrulls in my example because I have the pieces.

Team 1 & Team 2 same pt total (don't see any issue with upto 4 players). i would advise having access to reinforcements though.

Privately, Team 1 chooses a piece on Team 2, that chosen piece is the Skrull imposter. Write it down and place on/by your starting area.

Team 2 chooses a piece on team 1, writes it down and stores it too. This piece is the target. (You may want to set a point setting on this character as it could be too easy to pick off the 8pt Thug later on...)

Beginning of Round 3, Team 1 can now use the 'Skrull Imposter' for one action and attack any piece in range on Team 2's force. They are granted Running Shot if they're ranged or Charge if they're 0. This piece is then replaced with a Skrull piece (preferably a powered Skrull) who can then breakaway to the Skrull dropzone.

**I have no idea where the dropzone should be at this point**

If you're running 300pt teams (2 players =600pt), then you should have 600pts of Skrulls invade. place them in the drop zone.

Teams 1 & 2 now combine as one and carry on with their turns, pieces played by their respective owners.

Alternatively, these players agree on the best plan of attack for the Skrulls on their turn. Victory points are awarded for Skrull KOs at this point, so who the Skrulls target is irrelevant as Teams 1 & 2 now share a common enemy incl. PC, TA's etc...

If rounds 1&2 were heavy on your force, have 'back-up' waiting at your start area of equal or less value to substitute in. The combined team will have to carry any wounds it received into battle with the Skrull invasion.

Alternatively, lessen the total of the Skrull team to compensate.

Additional points.
You don't have to run a 'target' for the Skrulls, you're up against it as it is.

Technically both teams (or all teams) could privately name the imposter and then roll off at Rd3 for the grand reveal; thus, 1 of 4 possible pieces could be the spy.

NOT HAPPENING. (spelling)

Super Soccer

600 Pts/4 Actions

Teams MUST consist of 6 characters

1 character (the Captain) may be over 100 pts. All other characters MUST be less than 100 pts.

The Captain will be granted Leadership as a Trait ability

Only one object is used in this game, the “Ball” which is placed in the center of the map. The “ball” is an indestructible object that may not be carried or moved by any means except by taking knock back. The “ball” has a defense value of 14 and always takes knock back equal to the damage it would be dealt. Give character a free action to make a close combat attack(kick) targeting the “ball”. When the “ball” enters a player's starting area, that player looses. Player’s characters may attack opposing characters as normal (it's a rough sport).

NO TEAM BASES
NO VEHICLES
NO RELICS OR RESOURCES
NO ATAs
NO FEATS/BFC

Calivnball!!!! Where the rules change every ten or 15 mins based on dice roll. Never know what rule will come up. Some maybe all black on the slots or only even points figs can move. Crazy with the regular rules.

I've basically done this kind of thing before using Battlefield conditions where people just make their teams (Say for 500 points) and then every 10 minutes a new BFC is drawn randomly and we have to follow what it says.

So, i finally got a chance to play test this co-op scenario game; below is how we played it:

Two 300pt teams start off versus each other.

Prep: Before the game starts, place 6 debris tokens, ensure only one is a 'Special' marker & place them face down randomly across the map.
Write the names of all pieces on a pieces of paper, fold them and place in a hat/pot.
You will need to put a third team to one side also...

The goal at this point is to 'Find the Document'.

Play commences as players race to 'uncover the truth'. When a character lands directly on top of a marker, they can have a free action to roll 4-6 and search the debris. To keep tempo, no action is required and opposing adjacency is not a concern.

When the Special marker is found, pick a name out of the hat. Switch that character with the Skrull Infiltrator. The Skrull Infiltrator gets the Hit & Run feat, allowing him to make a close combat attack and move up to his full movement towards the invading Skrulls.

Place the invading Skrulls on the left or right side of map on the central line.

The player teams are now considered friendly to one another and can share powers and Team Abilities. They are granted the feat Survivalist Resolve, where each player is allowed to use Regen on a piece of their choice as a free action. The second feat is "We Need Backup!", each player replace KO'd characters of equal or lesser points to rebalance the game to 600ptsv600pts

SUMMARY:
We really enjoyed the game, the marker turned up first, so not too much damage across our teams but it did mean we were still pretty on separate sides still.

The Skrulls faired very well and got a lot of Shape Change & Skrull TA rolls.

It may play better with 3 players (3rd controlling Skrulls) if 2 players cannot play impartially.

Anything I can use Phoenix Force Magik in.

Ran an Exiles team vs some of their adversaries last week.

The scenario was 500pts but you could replace any KO'd figs upto the cost you lost; the force always totalling 500pts

In Exile/Weapon X theme, they had had to defeat rifts in time across the map. Represented by x3 tokens at any one time.

50pts a token.

The goal is to seal the rift by using a free action when adjacent to close via a 2d of 9 or higher.

If you fail a power piece steps thru and has Power Cosmic and Indom on their turn.

Rifts re appear so that 3 are always present.

Only x3 power pieces on the board at any time

Rifts rupture after 3 full turns if no attempt to seal is made upon them.

X6 power pieces are set aside pre-game, number them 1-6 and a D6 determines who enters.

Winner is the one with most rifts sealed or points if the scenario runs until each players replacements runneth out.