Goldar and Rito are normally shown as incompetent, but this event was intended to be an end for the old rangers. So it shows they actually have enough ability to pull this kind of thing off when they really put their mind to it. One ranger alone would not be enough to regain all the coins when the bad guys manage to sync up just right.
However, they had the device and ran with it before getting it taken from them. All they had to do was remove the coins as they ran, in case the device was taken. It's their own stupidity that led to losing the coins, regardless of if Billy had gotten his out already.
If they did get them, the bad guys likely would have retreated due to their only plan failing, and the rangers would return to the command center. If only he had his coin, they would still probably be brought back.