SI's DOOM's Powerless ability says he can counter all powers and abilities. Now I know in the Outwit discription it omits TA's but this power is not outwit so can DOOM counter TA's as well???

Also where in the rulebook does it state that wild cards can copy TAs but not share them back such as Sinister Syndicate???

1) No, it is still Outwit:

POWERLESS: Doom can use Outwit. When Doom uses Outwit, he can use it normally, or choose to counter all powers or all abilities of a target character 6 or fewer squares away.

2) I believe that it says it on the PAC under the description of those TA that allow replacement values: IE Defenders, Sinister Syndicate etc.

It does, but in a roundabout way: The PAC now makes a difference regarding whether a figure possesses the team ability (in other words, has the actual team symbol) or merely uses it (like wildcards and Mercenaries do).

Nope I don't see it where does it state that, about the Wildcards I mean.

You just need to read the PAC. For example, let's see the Defenders team ability:

"DEFENDERS™ Before any attack roll, a character using the Defenders team ability can for the attack replace its defense value with the unmodified defense value (including a replacement defense value) of any adjacent friendly character possessing the Defenders team ability."

Characters with the Defenders team symbol possess the Defenders team ability. Wildcards can only use this team ability.

Therefore, characters who have the Defenders team symbol can lend their defense value to characters using the Defenders team ability (wether the latter are wildcards or actual Defenders team members).
Wildcards can only borrow the defense value of friendly genuine Defenders (i.e. characters with the team symbol), but wildcards can't lend their defense value to other Defenders.

Hope I'm being clear enough.

So for doom's powerless he still needs lof even if he is outwitting all powers i.e. stealth?

Yes. It requires a "target character" to use it on, and to target a figure, you need LOF