does anyone know of where to find/if there even is a complete guide to all items that can change your pet's species and/or colour? not just elixirs and potions but things like mystical dolls, magic wands, potion-like items (e.g. Experimental Dew), plushies, filled bottles/flasks, aeanoid seed, etc.?

There's a list of most, if not all of the transforming-capable toys and plushies in a thread in the Suggestions forum. I'll link it in a sec. Found it:

Update these multiuse plushie/toy/elixir items!

thanks for the link. looks like i've gotten everything on that front. hope the items aren't removed from the site or at least changed to something more appropriate.