I didn't find the answer while searching this forum.

You have Echo Caverns in play and won the Edge. You have an AAC-1 Speeder Tank. The opponent have Darth Vader (TDOH) and Colonel Stark.

Can you put the focus token and Vader and in action window, focus Echo Caverns to remove the blast icon from Stark and add it to Vader's, preventing Stark from using it?

I didn't find the answer while searching this forum.

You have Echo Caverns in play and won the Edge. You have an AAC-1 Speeder Tank. The opponent have Darth Vader (TDOH) and Colonel Stark.

Can you put the focus token and Vader and in action window, focus Echo Caverns to remove the blast icon from Stark and add it to Vader's, preventing Stark from using it?

As far as Echo's readyness, its action can still be used if the card has a focus token on it from being resourced, correct? And I'm assuming that neither of the two targets have to be ready (although it would obviously help if the one you were transferring the icon to for the battle was)?

Echo Caverns cannot use its Action if it already has a focus token. The cost to initiate the Action is "focus this enhancement," and you cannot focus something if it is already exhausted.

Neither of the units targeted need to be ready, though the ability is generally only relevant if at least one of them is ready.