McFarlane NEEDS to get rid of his Bat-obsession.

 So far ALL 2-PACKS have had a Batman theme

ARKHAM games Batman vs Joker

Red Hood vs Nightwing

Flash vs Red Death (a Flash-Batman hybrid)

Hal Jordan vs Dawnbreaker (a GL Batman)

Superman vs Devastator (Doomsday Batman)

While Nightwing and Red Hood aren't Batman, they are members of the Bat Family.

Now here's how these Two Packs would've been more appealing to people who aren't reading Dark Knights Metal, or don't want repeats of non-baf Batman variants just to get the other characters. Problem is that most of these packs are just redos with a different head. So, we need to make them more appealing:

Arkham 2 pack and the Red Hood vs Nightwing pack don't need changes. I'M Looking at the other three:

Flash vs Reverse Flash:

This one is ridiculously obvious. A Flash vs. Gorilla Grodd to pack could work but it doesn't have the same Flair matching Flash versus Reverse Flash because Grodd is not Flash's "mirror image".

Green Lantern vs. Sinestro:

Again it's an obvious choice and since both characters haven't had previous releases, this makes the 2-Pack twice as enticing.

Superman vs Doomsday:

Why use the Batman themed imitation when you can use original? 

This doesn't change the fact that the two packs are still enticing and they are free of flying vermin... if Todd still wants to do something with Batman we can go for a very classic 2 back that is simply repaint and maybe some alternate sculpted parts:

Knightfall: Batman vs Bane

Bane requires new lower legs, forearms, hands, and head. Of course he'd be repainted in classic colors. Batman would be a repaint of the vanilla Batman. Add a special base to recreate the Breaking the Bat pose.

Or, how about a special "Batcave 2-pack"

Batman (with interchangeable heads) and Alfred.

While Alfred would require new tooling some of it could be reused for other characters like Riddler, and other suit wearing folk. 

The base would be a semi-flat "Batcomputer" and a "bat-chair" for Batman to sit on and have his cape drape over the back. The idea is to have McFarlane delivering the toughest part for a Batcave Diorama, the Batcomputer. Making a cave backdrop is easy. Mayne add some accessories for Alfred like a teapot and cup and a shotgun.

Or if a Batman needes to be released fighting a Green Lantern, then Guy Gardner is your, uh, guy...

Hell, a Red Robin vs Robin 2 pack would be interesting. You get a variation of Damian (thinking hood up outfit) vs Red Robin. You complete the Bat Family and have a 2-PACK to balance the Red Hood vs Nightwing pack. 

I'm mentioning Bat-stuff because that's  what makes Todd's pee-pee hard.

They can easily make Superman 2 packs:

You have Superman, Supergirl, Steel, Suoerboy, Eradicator, Cyborg Superman, Luthor, Zod, Brainiac, Lois Lane, and Jimmy Olsen, Doomsday, Mr. Mxyzptkl, Parasite... etc. The point is to stop with the Batman