Can potions that alter a pet's appearance (Angelic,Reborn etc) be obtained from any other source than the Potion lottery?

Yes they can be. You can get them from user shops, Random Events and the token shop. :)

Potions are available all sorts of ways, it just depends on which one you want. Some are in the Millionaire Center (Darkmatter), Some must be made at Asmodeus' Lab (Glacier, Nuclear), some are in the Token Shop (Reborn, Spectrum). And, of course, you can always buy them from the user shops.