Afternoon,
Is it possible to Tbolts and Avenger to have the FF TA and then use the alternative UFF TA to share defense values?

thanks in advance,
Nick

You cannot use Thunderbolts to give a character an Alternate Team Ability from a Feat card. They will have the original team ability even if you have other figures on your team with the ATA.

T-bolts may use any team ability except wildcard and team abilities that are not wildcardable

In order to be assigned an ALTERNATE team ability, you must have the team symbol printed on that character's base

So if you declare the T-bolts to have FF, they get the original vanilla FF