[E19 Spoilers! - E19 Pokemon Locations Spreadsheet - All Wild and Event Pokemon, TMs, and Passwords]

Klefki can be obtained before the fight with Adrienn instead of before Titania as the document suggests. 

It should also be noted that in order to get the classified information, you need to return a diamond ring, which can be found while diving in Azurine Lake.
Can't remember exactly which dive spot it was, and I can't remember if you need to find the key for it.
There's also a battle when returning the classified information to

Spoiler

Looker

And the difficult battle is more specifically a double battle

[V9 - Bug Reporting Thread]

10 hours ago, Zargerth said:

That's how Shadow Pokemon work. They have moves they cannot learn.

Ah I see thanks. Well I ended up using her to breed to get a quagsire with recover for the electric gym. Oh wellz

[V9 - Bug Reporting Thread]

Welp i'm back again but I'm even more confused. Just purified this quagsire and apparently it has flame burst... No idea if this has been reported already, sorry if it has.

 

EDIT: I also realised that Quagsire doesn't even learn water pulse or refresh naturally or from purification

[V9 - Bug Reporting Thread]

Decidueye learns Steam Eruption instead of Spirit Shackle on evolution lol. It appears that way in move relearner even. 

 

No screenshots for when it evolves unfortunately

 

[Pokémon Location Guide v3 (Episode 16)]

Furfrou can be found in Ametrine City as well