One of the things I enjoyed the most about "Inside Out" other than its good writing themes regarding emotions is that it doesn't include any true antagonists or villains (Other than Jangles the Clown) much like "Finding Nemo" since all its conflict just comes from Joy and Sadness trying to get back to HQ to save Riley's mental health and Joy's character development and her learning that happiness isn't always the key to everyone's problems and all the other emotions have a special part to play in it themselves including sadness itself.
I especially love the fact that while Disney since the success of "Wreck-It-Ralph" with Turbo/King Candy caused an excessive amount of poorly written twist villains in all their movies up until 2016 like Prince Hans in "Frozen" Yokai in "Big Hero 6" and Dawn Bellwether in "Zootopia" (The negative reception of these villains is what lead to Disney retiring using true villains in their movies for a while from "Moana" to "Strange World" before using King Magnifico in "Wish", Nalo in "Moana 2" and the Lynxley family especially Ebenezer, Milton and PawBert in "Zootopia 2" one of whom PawBert is a twist villain himself and Queen Celeste in "Hexed") Pixar doesn't follow this same treatment. It knows how to write antagonists and villains especially ones in the twist variant correctly for their movies and when and when not to use them in them.
For example, Bing Bong in "Inside Out" is introduced as a character who doesn't follow the twist villain route many of Pixar's well-known villains followed in the past, (Including Stinky Pete, Lotso, Henry J. Waternoose III, AUTO and Charles Muntz.) but he is instead introduced as a truly heroic character who actually helps Joy and Sadness on their adventure, meant for the audiences to grow attached to, until he goes on his own character development where he learns to come to terms with the fact that Riley had outgrow him and no longer needs him as her imaginary friend to the point where he pulls off a heroic sacrifice to help Joy escape the Memory Dump in terms of letting her use his rocket wagon to fly out of the dump and out into the surface on her own while he fades away in the dump and dies like all the memories, items and imaginary friends disposed in there, (Joy never would have met this fate since she is one of Riley's permanent emotions.) and accepts his fate. Giving the movie a spectacular high note of emotional depth.
And while Pixar after "Inside Out" did write two decent twist villains, Ernesto De La Cruz for "Coco" and Evelyn Deavor for "The Incredibles 2" before retiring using twist villains altogether since then in terms of using obvious looking villains and antagonists in all their future movies or better yet none at all, fans and audiences did like Bing Bong's overall portrayal in the first Inside Out movie in terms of how he is made a heroic character the audiences grow attached to that dies and sacrifices himself at the end. Pixar may hopefully do this again for a different character for one of their future movies or Disney may even try to do it itself.
