Jafar vs Aladdin

Rasputin Battles Flynn Rider
Flynn battles with him to get the Lam and turns into The Bear from The Fox and the Hound

Nightmare Moon Battles Rapunzel
Rapunzel battles with her to get the Lam and turns into The Bear from Balto

Shere Khan Battles Danny
Danny battles with him to get the Lam and turns into Dragon Maleficent from Sleeping Beauty

Messina Batlles Sawyer
Sawyer battles with her to get the Lam and turns into The Dragon from The Pagemaster