Scenes with the alligator and the knight don't exist yet, but they'll be coming out over the summer.
For the Kobold, you either need to be small (small in general, not just smaller than him) or you need to wear the wizard hat that you can get from the cobra.
There's a scene you can get with the bat and shark if you talk to them at the bulletin board at night with at least one of them interested in you. For that to happen you either need to flirt with the shark and then apologize to him or talk to the bat about something he's interested in and then ask him to do something else once he's at stage 3. After the scene with them together you can get scenes with them individually by repeating the things that got them interested