The best you can do at the moment is take care of them as much as possible. Help them to physically heal. Bond with them a bit. Focus completely on helping them recover from their experience. They’ll let you know when they’re ready.
And they’ll let you know if they seem interested in other people. In order to determine this, after they seem well enough in a physical sense and after the inevitable symptoms of anxiety (namely, skittishness around humans, separation anxiety, and so forth) subside, you may begin seeking new trainers for them. Advertise their availability through shelter networks or social media, then meet with the potential trainers. Be sure to do background checks whenever possible and select from your potentials the ones who seem most capable of giving the rattata and zubat adequate enough care. Then, introduce the pokémon to each trainer and allow these trainers to interact with them as much as possible. If the rattata and zubat seem comfortable enough to interact back, then they’re ready to be rehomed. If they act skittish instead, thank the trainer but inform them that the pokémon are not yet ready. A good trainer will understand. You may even be able to set up times for the trainer to return and continue to bond with your pokémon if they’re passionate about giving them the love and attention they deserve.
In short, it’s a slow process, and you may need to do quite a bit of work to determine whether or not they’re ready. The point is, focus on their recovery first and allow them to tell you when they’re ready.
Best of luck, anonymous.