Goldfish are failry adaptable to a range of tempratures and
environmental changes and water quality.
However each immediate and drastic step may prove fatally stressful for
the fish.
Since the goldfish have always lived in a tank I would suggest that you
give them to your trusted Aquarium shop and request them to put a small
label on the tank stating as (Tank use only)
The pond is not a very good idea.
1- They may not be able to adapt to the ponds ecology
2- They will stand last in the ponds hierachy, Now you do understand
how that feels like.