Say I use T-Bolts to copy Defenders. Can they use it WITH regular Defender figs or are they still considered Avengers, and thus can only use it with other T-Bolted Avengers?

Like, JSA and Defenders can't work together because they are different teams yet have the same ability, is it the same for T-Bolts? OR are they more like a Wildcard and they can use the ability of the parent TA?

If they have "Tbolted" to be a Defender, then they can interact just as if they were a Defender, with one exception...

If a 2000AD or Ult X-Men figure claims the Defenders as their enemy to get the +1 attack bonus, then the Tbolts would be safe. To get the bonus against a Tbolt, those teams would have to declare Avengers as their enemy.

This is a question that gets asked a lot, Funky_Jett has the current Ruling correct.

I think WizKids should look into the ruling and make a correction so that it acts more like people expect, Per the reading of the card and the Feat Card Rules.

Hopefully someday in the future WizKids will look into this and see how confusing it is for those who Read the Card and Read the Feat Card Rules. Unless you frequent Boards like this you'll never come up with the ruling that has been made.