Is it possible to outwit the Stealth power given to a character using the Batman Ally team ability?

The team ability itself does say they can use stealth not a effect worded the same and provided they aren't currently in stealth or you have a team ability letting you see past it could you do it?

It lets them use Stealth, not possess it, so the Stealth cannot be countered. If you are able to counter the team ability that would work, but generally team abilities cannot be countered.

Some characters can outwit team abilities, such as GG032 Adam Warlock.

COSMICALLY UNKNOWABLE: Adam Warlock can use Outwit, and he may use it to counter team abilities. If he uses it to counter the Power Cosmic team ability, he can use Outwit again after actions resolve to counter a power on the same character.

Right, there are a very few. But it requires being able to counter team abilities to be specifically called out, and that's rare.

As Necro says, you can only Outwit things that a character possesses. If, for example, Batman had a trait that said "Batman possesses Stealth" you could indeed outwit that, if you could see through the Stealth (thank you, Zibarro, my go-to stealth-buster)

Maybe you can look for characters that say you cannot use Stealth or team abilities (which would nerf Batman Ally)

Two-Face from the Gotham City (HARVEY OR TWO-FACE?: Opposing characters within 4 squares can't use Stealth) and Dirk Anger (INSANE LEADERSHIP: Dirk Anger can use Leadership. Other characters can't use Leadership. Opposing characters within 4 squares of Dirk Anger can't use team abilities) can do these