Shadow Queen vs Queen Jaydes

Queen Jaydes was powerful enough to take out Mario in one shot and this is him after he went through the events of Thousand-Year Door if we follow a timeline, so there might be some credibility to this. She seems like a very powerful being who preferred to stay out of mortal affairs, which is why she did not just go and fight Bleck's group.

However, Shadow Queen was quite powerful and had Mario on the brink of death until everyone's wishes boosted his power and gave him a second wind. This is actually a pretty good fight.

Shadow Queen was sealed away, but I do not think she went to the Underwhere.

I wonder how strong Grambi is then.

I mean after Mario defeated her

Not much actually (he was having trouble with Bonechill)

Well it's possible that most kind of spirits just turn into shaydes as soon they come here (Mario & co avoided this because they were alive to begin with).

It could be a Dragon ball style kind of afterlife for souls (evil or rather normal souls turn into powerless husks, virtuous and unusually good souls are allowed to keep their original form)

Through personally i think Dimentio got erased from existance when Blumiere & Timpani used the Pure hearts.

Depend on how you interpret the "shadow of his power", if this shadow is really what left of dimentio, then he pretty much got erased along with the Chaos heart.

Otherwise yeah, he's probably in some dark sealed place deep in the underwhere...or in Tanabe's trash bin