Voldemort is the shadow because he is told to be very powerful and dangerous he also faced the hero in battle.

Rubeus Hagrid is the mentor because he's the one who told Harry that he is a wizard and helped him get his stuff for school. Also Albus Dumbledore was a mentor because at first he helped Harry in little ways then towards the end he becomes more involved with teaching Harry.

Uncle Vernon was a Threshold Guardian because he stopped Harry for going to Hogwarts, Fluffy the three headed dog was also a Threshold Guardian by sitting and guarding a door to the Sorcerers stone which Harry, Ron, and Hermione didn't know about. Professor Snape was the Shapeshifter because everyone believes him to be mean and rude and thought he was casting a spell to make harry fall off of his broom in the Quidditch match but he was trying to help Harry all along. The allies of the movie are Ron and Hermione because they were his friends through out the movie and helped him get the Scorers Stone. Harry's owl Hedwig was the mentor because he delivered Harry's mail and delivered news.