Just adding a yeah, at 100 gallons you'll want to stay away from the long bodied goldies and any koi. Could always consider fancy goldfish, 3 would do nicely in a pond once it is being filtered properly and would school together. They're very cute! Most anything else has to be moved inside when the weather gets cold, so you'd want to consider natives. I personally like "rosy reds," very pretty fat head minnows that add lots of movement to the pond and don't produce nearly the waste of goldfish. As long as the pond doesn't freeze they'd be fine all year! Also great mosquito larvae eaters, but can be eaten by dragonfly larvae.
If you went fishless, you could consider crawfish. Only mentioning this since you mention ghost shrimp. They need lots of hiding spaces, you can't put too many or else they'll kill each other all off for most species, and you won't see too much of them, but there are lots of color varieties through multiple species. My personal favorites are the dwarf crayfish, they get along better with one another than most and come in beautiful orange so you'd be able to see them. Just check to make sure the ones you're interested in can handle all the temps you think they would be put through first.
If you're down to bring fish indoors and can give them sufficient space during the winter, lots of tropical fish do excellently and breed lots if left in an outdoor pond. Favorites are mollies and guppies, they tend to breed profusely and don't make a habit of cannibalizing their own brood to the bone on numbers, so when fall comes around and you're catching them all you can select your favorite fish from the nets and sell the rest. Not a "get rich quick" kind of thing, but maybe enough to make back their food for winter.
If all else fails... it could make a lovely plant collection. I grow lots of fast growing stuff in our pond, hornwort and parrot's feather, java moss and duckweed. Great snacks for my poultry when I remove the excess!
) or a pet turtle!
