So my question is if Colossus has no action tokens and uses Charge and does damage, the trait triggers to use Charge as a free action. What allows for using the close combat action as a free action the second time?

As your rules quote says, "unless the game effect indicates otherwise." The power specifically gives you a Charge after a Charge, so it works.

You can because the free combat action is nested inside of the Charge action.

Not asking about Charge in general, but more specifically about the ability to give the free action again to make the close combat action.

Do you mean like...charge -> exploit-> damage....then charge -> exploit ( is your question can you activate exploit Again?

Because it is part of the "Charge" action. By giving him the Free Action to use Charge, you get to use the entire power - from half movement to the close-combat action. Its all part of the power.

No, my question is what allows you to use the same free action twice? My understanding is because it's part of the Charge power and that supersedes the rule, correct?

Yes, there's a thread somewhere here about Flurry that answers your question in further depth.

Good that's what I thought you were talking about.

This is the Thread that the topic was brought up.