Okay, I've looked through the figure databases and found the following groups that could use Fastball Special fairly well:
Brotherhood: Juggernaught throws Blob or Sabretooth
Sinister Syndicate: Rhino throws Kraven
Injustice League: The General throws Solomon Grundy (I like this idea, simply because Spriggo used this team last week)
Teen Titans: Troia throws Cyborg (she could also throw Starfire, but that would be dumb)
X-Men: Colossus, Polaris, or Sasquatch throw Beast or Wolverine
The Avengers and the Justice League can do it too, but the possibilities don't excite me because neither has any really good people to throw.
I'd like to avoid X-Men, just because I used them last week, which leaves Brotherhood (a free move), Sinister Syndicate (share attack values), Titans (share damage clicks a la X-Men), and of course the Injustice League (free attacks when adjacent). Of course, once I have my fastball special set up there's no reason to stick to the same team (though it could be fun). I might go with Titans just because the figures required are relatively cheap, so I have more leeway to fill out the team with support.
Keep in mind that since this is a Fastball Special team, I'm going to use both my copies of Fastball Special. I though about borrowing Spriggan's, but it just seems silly.