yeah definitely the worm-on-a-strings hanging from your ceiling, but it would also be super cute to hide them in little clutter areas (if u have pets keep their abilities to reach those worms in mind) LED lights would be great for kidcore, and u would pair them with fake ivy for wormcore. sooooo many stickers for kidcore and cutecore, and a bunch of nostalgic plushies, specifically Sanrio, My Little Pony, and Care Bears. cutecore is just a ton of pink and white, again the overabundance of Sanrio themes and plushies.
overall, mostly neon pink and white with evident bits of rainbow, tho make sure it doesn't look too chaotic, worm-on-a-strings from the ceiling, a bunch of Sanrio and/or generally nostalgic and cutesy plushies... yeah! i'm no expert but that's what i would do so take whatever u want or none and i hope ur room turns out amazingly :D