I remembered having a vhs A long time ago that was animated. I’m not sure if it was a couple of shows on one vhs tape or a whole movie. In the beginning there’s a cat living in an attic being chased by something. the animation is different later on and there is a woman or a man in some kind of swamp like place and she transforms into a spider and a flamingo, I remember it looking very pretty in the second half.
Long shot but are you thinking of ‘The Sword in the Stone’ (1963)?
http://www.imdb.com/title/tt0057546/?ref_=fn_al_tt_1
The shapeshifting wizard battle between Merlin and Madam Mim