Steven Universe

Amethyst is one of the main characters from Steven Universe.

She's the youngest of the Crystal Gems until Steven was born, Amethyst has a rebellious and hedonistic personality. Her mischievous sense of humor often provides comic relief, and her fun-loving and relatively childish nature bolsters her friendship with Steven. Her amethyst gemstone, from which she can summon a whip, is embedded on her chest; she also makes frequent use of shapeshifting capabilities. Late in the first season, Steven learns that Amethyst (unlike the other Crystal Gems) was created on Earth as part of the Gem Homeworld's "Kindergarten" project to convert Earth into a Gem-occupied world; later on, Amethyst herself learns that the Kindergarten produced her malformed, smaller and weaker than other Gems of her type (the "Quartz warrior" caste). Her irreverent personality masks deep-seated feelings of inadequacy, resentment, and fear that the other Crystal Gems do not respect her; a long-term character arc involves her learning to respect herself and her capabilities.

Cat Fingers (S01E06)
The Purple Puma makes his first brief appearance as Amethyst is demonstrating her shape shifting abilities to Steven by rapidly shifting between a myriad of different forms - one of them being The Purple Puma.

Tiger Millionaire (S01E09)
Amethyst's wrestling alter ego "the Purple Puma" is revealed, where she turns into a muscular male looking character.

Ocean Gem (S01E26)
Purple Puma makes an appearance once again

Maximum Capacity (S01E43)
Purple puma makes a very short appearance in this episode

Reformed (S02E05)
Amethyst regenerates to have huge muscles in order to take on the monster.

Steven Universe Comic #1
Amethyst makes fun of Pearl by turning into a giant muscle version of her.