Something that comes up often in discussions is the fact people want new challenging late game dungeons and legendary recruits, so i came up with a idea to help both at the same time!
A brand new very long challenge dungeon which limits the number of pokemons and items you can bring in,
maybe just allowing 2 pokemons and 5 items!,
At the end room of the dungeon you can use heartslate’s like thier fossils summoning a recruitable boss version of the legendary of that heartslate, which can be done as many times as you got heartslates!
But! Rember the limited number of items you can bring in? this creates a fun risk vs reward situation where you can save yourself a lot of trips through the dungeon but you won’t be able to bring other useful items with you! do you bring a tight belt, 2 reviver herbs and a escape orb and 1 heart slate to make sure your trip won’t be at the mercy of possible bad rng? or do you just enter full confidence with 5 heartslates and save yourself a lot of trips at once?!
This method would allow heartslates to still very useful and valuable, since you can still use the mystery part for the original summoning, allowing players who can’t beat the dungeon to still use legendarys with the mystery part, while more hardcore players who want to recruit and personalize legendary or even shiny hunt them to still want heartslates, want a lot of them in fact!
the dungeon could also contain a unique currency called legendary dust that could be used in a shop to buy valuable items or maybe some new heartslates, or maybe even buy holidaycave exclusives! 