The good news is that there's still hope. Team Abilities get re-written all the time and often times revamped to be better than the original. Just look at the improvements made to the Masters of Evil TA or Titans TA.

Now that we've identified the problem, we can look at solutions. A total re-write is necessary to fix this terrible TA, but there are certain things that we have to keep in mind.

There are two basic types on Team Abilities: those that need at least 2 figures to work (i.e. JSA), and those that can work solo (i.e. Mystics). The Injustice League definitely fits in the "at least 2 figures" category... there's a reason it's called a "League".

In my opinion, the most appropriate way to fix the Injustice League TA is to simply reword it so it acts like the Green Lantern Corps ATA Feat card:

GREEN LANTERN CORPS: When a character with this team ability makes an attack against a target character, you can modify the character's attack value by +1 for each friendly character with the [Green Lantern Corps] team symbol that has attacked the target this turn.

See that? It works very similar to the current Injustice League TA, requiring one member to make an attack first. But subsequent attacks by additional team members gets an attack bonus rather than a lame "free action token".

I definitely don't want the Injustice League to follow the JSA or Sinister Syndicate model -- I'm not a huge fan of TAs that lend and borrow combat values. This is especially true here since Injustice League figures mostly have average combat values. I do like the Superman Enemy ability though:

SUPERMAN ENEMY: When two friendly characters that can use the Superman Enemy team ability are adjacent to each other, once per turn, the character with the higher point value may be given a free action. If you do, that character can use Outwit until the beginning of your next turn, if it cannot use Outwit already. If the two characters have the same point value, their controller chooses which is treated as the higher point character this turn.

A new Injustice League TA could work just like this one, but rather than Outwit, these team members could get Exploit Weakness and Psychic Blast -- this would boost their combat effectiveness without giving them the all-powerful Outwit (and it would certainly help with all those average combat values). Or if you want to keep it simple, just replace the "Outwit" with "Perplex".