I just got a fun idea on how to implement that: whenever King Slime would spawn, there's a chance the better stronger Queen Slime will spawn in his place instead, just like Pinky does with normal slimes, because King Slime will randomly keep spawning outdoors at the proper zone and is already bound to keep appearing whenever Slime Rain triggers, whether or not you care about him anymore, so this builds onto old mechanics for a bit more fun meaning instead of maybe just making a separate new boss that gets done once and forgotten
-Can't happen if King Slime hasn't been beaten yet, doesn't happen with the boss summon item (so it has to come by surprise at the forest or event, and, if you WANTED King Slime with the item then there's no chance of it going wrong)
-Stronger boss than King Slime, higher stats and different moves/strategy (and definitely not cheatable like King Slime), maybe could be a bretty tuff pre-hardmode miniboss or something stronger locked to only happen after hardmode
-Just a pink-colored version of King Slime, with a different crown design, and no ninja inside
-Maybe its size will constantly scale to its remaining HP so it gets smaller with smaller hitboxes as its HP lowers, and hurting it will split off new new pink slimes that will hop like normal slimes but every so often may pause to try to do one aimed shot at you (or, better, a charged aimed superjump at your direction because pink slime means bouncy). By the end it has no crown and visually it's just a Pinky, as if every Pinky is just a member of the slime community and there can be one alpha that eventually grows into being the de-facto Queen Slime in the terraria wilderness
It might have some "normal" loot but it would also have a couple just fun things that don't care where in the progression you are
-I'm not sure if I dig the bouncy accessory, but her expert item could be a pink royal gem that directly crafts with King Slime's so that it gets another effect on it
-Her crown as a vanity item for you, exactly as much pink gel as 1 Pinky, boss trophy (crown with pink splooge on the plaque, resembling King Slime's trophy, posed to obviously pair together if put to the right of King Slime's), same Solidifier as King Slime
-A pink slime mount that controls different to the blue one in some way (on the floor can hold jump to Mario2 charge jump farther than the blue one can, loses ability to auto re-jump on landing if holding the jump button, can still goomba stomp)
-Drops those little bouncy balls for playing, as a throwing weapon. Infinite use, melee damage, needs to hold button to charge force, maybe lowered speed while charging. Each bounces around with a little light trail behind, lasts for X seconds before fading or if too much momentum is lost. I imagine mostly for messing with other people like the slime gun and photobombing other people doing the golf minigame
