yep, if its deep enough. I started with 3 shubunkin. Now I have 20+ in my pond.They didn't breed in the small pond I had, but once they got into their new home..I guess they like it....the deep end is about 3.5 feet. I keep a deicer and air pump running all winter and they've been out there for 3+ years now...

Yep, zone 4 here, sometimes minus 10-20 for days.... I have a few shubunkins, gold fish and comets, 4 of them are 6-8", 28" deep pond. I keep a heater in it over winter.

I kept some over winter with no heat or air pump. They were in water two and a half feet deep by my estimate.

Yes and Yes

I have a few goldfish that have been reproducing each year. Last year I bought 2 shubunkins. My total was up to 19.
Now this year's crop of babies, I counted almost 17 new babies... but one of these was a strange whitish colour, instead of the usual brownish colour. All the brown ones are now starting to change to orange, but the strange coloured one has now changed into the white/black/orange colour of a shubunkin! So even though we have probably too many babies now, I'm excited that we have a baby shubunkin now for the first time .
(Geez.. what a coincedience that I bought 1 male and 1 female shubunkin at the time). Also you figure, if one shubunkin is born, I'm surprised that there weren't a few more... well I guess the odds were low, as they are outnumbered by goldfish).

Anyways, I'm really excited to have my first baby shubukin born in my pond.!!! My pond is 1500 gallons, and is only 32" deep, so I don't think that the pond has to be that deep. I also use a pump and deicer in the water (get about 8" thick ice).