Devoid

[An Angry Fatman]

Can a {Eldrazi Agressor} be countered with a {Flashfreeze}? Do these devoid cards have a color identity on the stack but not on the field, or is it that the card has no color wherever it is.

[Remillo]

Can a {Eldrazi Agressor} be countered with a {Flashfreeze}? Do these devoid cards have a color identity on the stack but not on the field, or is it that the card has no color wherever it is.

702.113. Devoid

702.113a Devoid is a characteristic-defining ability. "Devoid" means "This object is colorless." This ability functions everywhere, even outside the game

While the cards with devoid may have color identity, they are not colored.

[Nymuera]

Can a {Eldrazi Agressor} be countered with a {Flashfreeze}? Do these devoid cards have a color identity on the stack but not on the field, or is it that the card has no color wherever it is.

702.113. Devoid

702.113a Devoid is a characteristic-defining ability. "Devoid" means "This object is colorless." This ability functions everywhere, even outside the game

While the cards with devoid may have color identity, they are not colored.

does that mean that a devoid spell with a colored mana sybol cannot be used in a colorless commander deck?

Correct the color identity must match that of the commander. An {Inverter of Truth} cannot go into a {Kozilek, the Great Distortion} deck, but can go into a {Skithiryx, Blight Dragon} deck.

[Remillo]

Can a {Eldrazi Agressor} be countered with a {Flashfreeze}? Do these devoid cards have a color identity on the stack but not on the field, or is it that the card has no color wherever it is.

702.113. Devoid

702.113a Devoid is a characteristic-defining ability. "Devoid" means "This object is colorless." This ability functions everywhere, even outside the game

While the cards with devoid may have color identity, they are not colored.

does that mean that a devoid spell with a colored mana sybol cannot be used in a colorless commander deck?

Correct.  Color Identity and Color are totally different things.

[Remillo]

however! {TRANSGUILD COURTIER} CAN be in a colorless edh haha isn't that cray

Nope.  It's color identity is WUBRG, but it has a characteristic-defining ability that makes it so.