I am doing a fishless cycle and it's painfully slow; likely faster than a fish-in cycle but once you start you are committed for at least a month or longer. I am not sure if any fancy goldfish are recommended for a new pond or tank cycle but on the other hand you don't want to get a different type just to cycle and then what?
I've had 3 comet body goldfish, started with 5, 2 lost to predator, had babies and both that grew to adulthood were lost to disease. I cycled my 60 gallon with the initial 5 and they did okay through it; I won't say great because they kept jumping out at every opportunity and I don't know why they did this.
I think you'd be okay (for a few years) with 3 comets or shubunkins, single tailed, or any combination of them but eventually they would outgrow the pond. The good news is you can start planning years in advance on needing it.