Nice! I did a no movement challenge with Anya a few days ago on Stage 3 Hard. Here was my final setup. Weapons: Main Lv7, Spider Cooking Lv7, CEO’s Tears Lv7 Items: Headphones, Full Meal, Breastplate, Body Pillow, Gorilla’s Paw, Membership At the beginning, it seems you may have to get Spider Cooking from the first level up. Otherwise, the initial Matsurisu will quickly defeat you. The second major hurdle is the mini-boss Matsurisu that shows up at 2;00. The best way I found to deal with this min-boss and the Reddit-niki Pacifist that spawns shortly after is to have level 5 or 6 Spider Cooking, at least level 1 Headphones, and level 1 or 2 Gorilla's Paw. It seems that it is important to defeat the regular enemies fast enough so that they don't stop the mini-boss from being knocked back by the Headphones. You will likely have to use the special at about 1;00 to defeat the Reddit-niki Healer and to have the special back up in time for 2;00. The CEO's Tears and the Body Pillow could potentially be replaced with EN's Curse and Piki Piki Piman. Gorilla's Paw is likely vital for the early game since Anya has incredibly strong synergy with them and they help out a lot for the rest of the run as well. Also, at 23:06 projectiles from enemies that are defeated or despawned will not deal any damage. This can also allow you to avoid projectiles by alpha striking ranged enemies before their projectiles reach you, such as with a hyper offensive build.
Very nice! My biggest issue with Anya was the damage, so I can see Gorilla's Paw making the difference. I'd manage to get through the miniboss with tank items and luck, but get swarmed by the Miteiru right after. Then I'd try building damage and get popped. It really is a matter of persistence and finding what setups work.
I only managed with Mel. Her bats can take care of early game with some good luck and her healing is great in the late game. I'm sure it's possible with others as well, but it might be a lot more difficult.