On the ICWO card it says that "You may remove Oracle from the battlefield..." and in the rule book it says that Wildcards can copy TA's on the Battlefield, so if you remove Oracle from the battlefield does that mean her Bat Ally TA is off limits to wildcards?

I would assume so.

No, the ruling on Oracle on her card is that she's NOT on the battlefield and wildcards cannot copy her TA.

I would have to say no. ICWO says specifically that you remove Oracle from the battlefield, and the rulebook states that Wildcards can use any friendly team ability on the battlefield. It seems kind of stupid, because you are putting points into the character with the team ability, but can not make use of it. I may be wrong, and would like to know for sure.

Correct. Her TA is out of play.

There is one way around it though: If you play the Loyalty BFC it goes into effect before Oracle leaves the battlefield, and wildcards are therefore allowed to choose her Batman Ally TA and keep it for the rest of that game.

Good call with that one, I love how Loyalty works around so many things like that.