haven't posted here in a while, have I? :,D Welcome to all the new members!
@Wren
There's two elusive items you can try getting, I'm bad at explaining things but hopefully this'll be understandable ;w;
Abandoned Quiche: In the second(?) room containing Bridge Flowers, there's a body of water in the bottom right of the room. Set up bridge flowers to the edge of the screen and you should get to a room with a bench. Check the bench to get the quiche!
Hush Puppy: Buy a hot dog from Sans, and in the MTT Hotel, slide it under the last door in the corridor of guest's rooms. You'll get the Hush Puppy! Make sure you DON'T have the hot cat in your inventory while you do this, because you'll slide that under the door instead and that doesn't do anything.
Also, if you want extra fights, go into the room in Snowdin Forest with the locked door (after the room you encounter Gyftrot in), and walk around NON-STOP for three minutes. If you stop just for a second you'll have to start over. I read on the wiki that the more people you kill, the longer it takes to get the special encounter, up to half an hour or something. I wouldn't recommend doing this on anything but the True Pacifist run.
I think this enemy is really hard to beat, it's the only one I haven't beaten yet because i'm a coward who refuses to do genocide so I haven't even faced Undyne the Undying or Sans yet haha. Come prepared!