The Battle Plan ability on the Utility Belt Resource states: If five or more Utility Belt items are attached, you may give the assigned character a free action and select an opposing character within 10 squares and line of fire; that opposing character can't use team abilities until the beginning of your next turn.

Would this also apply to ATAs as well?

Yes, ATAs are still Team Abilities. The Battle Plan on the Utility Belt will prevent a figure from using any TAs or ATAs it has access to. Note that this isn't actually countering the TAs/ATAs, which can be important in some cases. The chosen figure simply cannot use them for a turn.