Yureyu Key

[Bossdra 2]

Although this is not entirely game breaking or ruins the game experience, if you do the solosis event and grab everything else, you are able to access the rotom room despite needing the getting it after you get fly. In fact, the key item is spawned into your inventory.

[Swampellow 116]

What exactly do you mean? The key was added back to the Wasteland Wall intentionally.

[Walpurgis 501]

Yeah, as swamp said the location of the key was intentionally changed back to where it was in earlier episodes. The other quest now has a different reward.

[Q-Jei 800]

If we must be as accurate as possible, the quest given by the old man in Neo Peridot Ward now allows you to get a Venusaurite instead of the Yureyu Key as a reward. As for the key itself, it’s now supposed to be found at the top of the Wasteland Wall.

Spoiler

As from episode 18, you have the possibility to make your way to Rotom in the Abandoned Power Plant as well as getting the TM95 (Snarl) even before to go to Agate City.