Stray Injured Cat Around the house?How Can I help?

Yes, the best thing to feed him is wet food if he has weak teeth and you should try and get him to the vet ASAP. So, even though it seems like a mean thing to do you will get him away from the outdoor dangers. So try and earn his trust then get him to a vet. You could earn his trust by putting out some food for him and showing him you wont hurt him, crouching down usually works. Try and find what he responds to like clicking or patting, that type of stuff. If you can't get him to the vet then try and make him feel safe and welcome, don't let your cats hurt him or 'gang bash' him because he will be very weak but as I said before try and get a vet appointment ASAP