Where can i find the other white monster, which Looks like an Angel? I already have Leviathan:-)

If you go a bit northwest of Windon, you’ll see a spot on the mountains up there. You can find a Cherub, which evolves into the Cherubion you’re looking for. Note that it is fairly rare and may take quite a few tries!

Also, I deleted the duplicate topic you made. 

Thank you very much!