The best birds you can get to chase off geese from a pond are Egyptian geese IMO. They do not like to share their area with any other bird. Mine tolerate my swans and cranes but anyone else gets run off.... they hate my Canada geese..... And any wild geese that try to land here get the boot as...
Black swans are more tolerant of other fowl, but white swans and others do not like to share their water. I would get an adult pair, as babys raised with other fowl would defeat the purpose.