NO Planaria kills hydra as well as planaria, but it also kills snails and I expect it would kill the copepods too. Copepods won't harm anything, though, they aren't big enough. But if you don't like seeing them, well, No planaria will probably do them in.
If you remove Hydra by hand, be very careful not to damage one. Every cell can produce a brand new Hydra, as they are immortal.
Native North American planaria are also not the voracious shrimp killers they are reputed to be. But south east Asian planaria species can get to over an inch and quarter long, though, and THEY can kill adult shrimp, baby shrimp, whatever they like. Even so, they don't actively hunt shrimp.. it's mainly a case of being big enough to eat the adult shrimp if they happen to find a vulnerable one. I've seen a tankful of them with Sulawesi shrimps in it, and the shrimp ignored them completely. The Asian planaria appeared to ignore the shrimp too, spent their time gliding over glass and rocks mostly, eating biofilm, it appeared.
Native North American planaria are mainly a danger to newly moulted shrimp, who for a short time can't move after they moult, and the odd newborn, who may not be able to get away fast enough.
But healthy adult and sub adult shrimp are in no danger from our small planaria species. Whatever planaria eat have to allow the planaria to digest them slowly. Planaria have no claws, no teeth. They have a simple mouth only, in the middle of the underside. They secrete digestive juice through the mouth onto their prey. They glide around hoping to land on something they can eat, but they don't hunt shrimp specifically. But if you have large numbers of them, then they can cause problems simply because their chances of finding new born shrimp increases with their numbers.
Hydra do not hunt shrimp either. They sit in fixed positions and simply react to motion near their tentacles. Like jellyfish, they shoot nematocysts, tiny stinging darts, if you will, that contain toxic venom. This can kill a baby shrimp that gets too close to them. It won't usually harm an adult shrimp.. but they are still not nice to have around. Baby shrimp are too big for most Hydra to consume, but they are not smart, they sting anything that comes close.
Fenbendazole is another choice that will kill hydra and planaria. Shrimp safe, fish safe, but may kill snails.
