I´m gonna list the locations of the monsters.

[Kookaburra]

I answered some of these in your thread, S19Mags. ^^

The angel used for Luxknight and a few others were answered by Jason here:

@Jason

Nilox: in the wastelands area where Dahag is, I think in the mountains near the northeast.

Musharoo: on one side of the broken bridge at the south of the wasteland, I forgot which side. I think the wastelands side.

Cherub: north of Windon, if you go kind of northwest you’ll find a spot on some brown mountains. That’s where it is.

This is what I recall from my memory, at least - provided none have changed positions since beta. 

The “skull” t-rex… I’m not sure which one you’re talking about, as there are three: thickskull, sledgeskull, and skullrex.

Thickskull is found in the forest southwest of Windon. 

Sledgeskull evolves from thickskull.

Skullrex is found in the forest northwest of Crescent Island.

Good luck everyone!