Ho-oh can be found on Mt. Wind 19F
10
mt mistrall
If you go to Spinda Cafe and buy a drink, Mt. Mistral may be engraved on the bottom of the glass
The nightmare Then the spacial rift(also known as the sky rift)
You have you make drinks at the spinda cafe
Mt. Travail 1F - 19F Very Rare
no there is not a boss and here is something that might help you Pokemon explorers of time, darkness, and sky all do not have bosses.
about 20 floors
i do not have explorers of sky
You go into azurills nightmare, go to spacial rift and fight darkrai in dark crater. After you beat darkrai, you can evolve.
neither routes are that hard i chose mt horn simply because of the name lol! (niether dungeon has a boss so dont worry.)