Holy shit could this game have unforgivingly hard levels. The game itself isn't too bad (although Sky Pillar is already pretty annoying), but some of the post-game dungeons are absolutely brutal. Especially those 99 floors dungeons like Purity Forest that can some mind-blowingly restrictive rules:
>You enter the dungeon at level 1 and a reseted I.Q.
>You can't enter with partners
>You can't enter with objects and if you do, you automatically lose everything
>Pokémon in the latest levels are around 25+ so you'd have to catch up by then
>Pokémon in the first levels yield shit for experience so grinding becomes quickly a slow nightmare
>Traps all over the place where you can get poisoned, losing your PP, get your items destroyed, activate an explosion, and so on
>The stress of encountering monster houses which can automatically fuck up your entire mission
>Darkness so you can't see some of the enemies going towards you
These have the hardest levels in any Pokémon game easily. Absolutely anti-casual if you wanna complete all the friend areas.