At the beginning of Toy Story, Woody and Buzz were originally rivals with Woody showing jealousy toward Buzz for apparently being replaced as Andy's favorite toy and Buzz thinking himself to be a real space ranger. Their misunderstanding of each other eventually results in getting separated from Andy, captured by Sid, and subsequently taken to his house. After Buzz finally finds out that he is a toy, he becomes too depressed to help Woody, but with Woody's words of encouragement, Buzz gradually comes to terms with what he truly is, and the relationship between the two starts to improve. After Woody saves Buzz from Sid's clutches, Buzz thanks Woody as they shake hands, and their friendship is born. The two toys then work together to reunite with Andy, and by the end of the film, they become the best of friends.
In Toy Story 2, after Woody is kidnapped, Buzz vows to rescue his best friend and goes out on a mission to bring him back home. When he finally catches up with Woody, he becomes upset with his friend's decision to stay with his group and leaves him to contemplate his decision, as Woody has become convinced that Andy will eventually give him away. However, when Woody comes to his senses, he calls to Buzz to inform that he is going home with him, to Buzz's relief. After returning home following a successful rescue mission, Buzz asks Woody if he is worried about Andy, to which Woody, who has now embraced the fact that Andy will outgrow him, replies that he will still have Buzz by his side.
In Toy Story 3, the two have a falling out when Buzz declares that he and the other toys, believing that a now college-bound Andy does not want them anymore, are going to Sunnyside Daycare after being mistakenly thrown out by Andy's mother, which Woody has witnessed. When Woody declares his intention to leave Sunnyside to go back to Andy, Buzz offers him a handshake, which Woody refuses, upset that his friends have seemingly given up on their owner. After Buzz is reset into Spanish mode, Woody convinces Buzz that the toys are "amigos" to get him to rejoin their side. When Buzz is restored back to normal, Woody, as with the other toys, is joyous that he has returned. After the toys are dumped into the furnace at Tri-County Landfill, Buzz and Woody take hands and glance at each other for what could have been one last time if not for the Squeeze Toy Aliens controlling a giant claw that rescues the toys from the incinerator. Soon after returning home, Buzz and Woody shake hands, unable to admit that the two best friends are separating ways after all they had been through. However, Woody leaves the note for Andy telling him to donate the toys to Bonnie, and after they are handed down to her, Buzz comforts Woody as they accept that their time with Andy is now complete, see that they still have each other, and begin their new lives as Bonnie's toys.
When Buzz first revealed himself to the rest of Andy's toys, Rex was relieved that he wasn't a dinosaur and further expressed curiosity over the functionality of Buzz's buttons. Buzz didn't seem to mind and later on, they bonded with each other when Buzz gave Rex some tips on how to be more scary, tips which helped him let out a loud roar at Mr. Potato Head. Rex was horrified when Buzz was accidentally knocked out the window by Woody but loyally stayed awake into the night in an effort to find him (though with no success).
In Toy Story 2 Buzz is shown to help Rex with his video games and gives him tips on how to defeat Zurg. He even encourages him by saying "You're a better Buzz than I am." When Woody is later kidnapped by Al McWhiggin, Rex accompanies Buzz and the others, thinking his video game experience has prepared him for real life combat. When they're in Al's Toy Barn, Rex, like the other toys, mistakes Utility Belt Buzz for the real Buzz but becomes overjoyed when the real Buzz meets up with them again in Al's apartment. Rex would later serve as Buzz's navigator when they hijack the Pizza Planet Truck in pursuit of Al to the airport, successfully getting them to the airport, though he has a little trouble identifying left and right.
Just like Rex, Slinky and the rest of Andy's toys were excited about Buzz. He was petting Slinky during the song Strange Things. Slinky was worried when Buzz was accidentally knocked out the window by Woody but loyally stayed awake into the night in an effort to find him (though with no success) Even worse, he fails to save Buzz and Woody from Scud.
In Toy Story 2 Slinky is shown up to find Woody's lost hat from Andy's dog, Buster. When Woody is later kidnapped by Al McWhiggin, Buzz and the rescue team use Slinky as a bungee cord to spring down and save Woody. When they're in Al's Toy Barn, Slinky and the other toys, mistake Utility Belt Buzz for the real Buzz but becomes overjoyed when the real Buzz meets up with them again in Al's apartment, and gets pat on the head. Slinky took over the pedals when they hijack the Pizza Planet Truck in pursuit of Al to the airport, successfully getting them to the airport. He, Buzz and the rescue team successfully saved Woody and beat Stinky Pete, but they were unable to get Jessie out of the bag.
When Bo Peep met Buzz after Andy received him as a birthday gift, she was impressed by all Buzz's gadgets and skills. After he did a "flying" stunt, Bo declared she wanted Buzz to be her "moving buddy." Buzz and Bo did seem on friendly terms as he quickly gained a popular reputation amongst Andy's toys. When Buzz tried to stop Sid Phillips from destroying a Combat Carl, Bo stopped him, worrying for his safety. After Buzz was accidentally knocked out the bedroom window, Bo did not blame Woody for it as she believed him to be an accident. However, when she sees Woody holding Buzz's severed arm, Bo screamed in horror, thinking Buzz had been killed. But when she sees Buzz riding with Woody on RC trying to catch up to the moving van, she was relieved and realized Woody was telling the truth. Buzz continued to remain friends with Bo as he noticed her attraction to Woody.
In Toy Story 2, Buzz continued to remain good friends with Bo. Before leaving to go rescue Woody from Al McWhiggin, Bo gives Buzz a kiss on the cheek for Woody, which Buzz awkwardly says he wasn't sure it would feel the same giving Woody the kiss. After successfully rescuing Woody, Buzz was still on good terms with Bo, as he supported her relationship with Woody.
Before Toy Story 3, Buzz worked together with Bo to rescue RC during a thunderstorm. However, when Bo was sold and bought by a buyer, Buzz was devastated to see his good friend taken away.
Buzz's relationship with Jessie is only hinted at the end of Toy Story 2 when Buzz became instantly lovestruck with her looks and her adventurous personality. Jessie immediately returns his compliments by describing him as the sweetest space toy she has ever met.
In Toy Story 3, their relationship hasn't evolved much since Toy Story 2, but it's shown that Jessie is fond of Buzz, and he is protective of her. After their "Operation: Playtime" plan fails, Buzz gives an exceptionally sad look to Jessie as she climbs out of the box, and also gives her sympathetic looks when she has panic attacks and when they argue about going to Sunnyside. Before getting taken to Sunnyside, Buzz is shown being a little more concerned over Jessie when she goes into a panic attack and says "We're being abandoned!" Even later, in the demo mode which he is put in by Lotso and his minions, he remains attracted to Jessie, calling her a "temptress" with "bewitching good looks". Then again, after being reset into Spanish Mode, Buzz is shown to be even more attracted and open toward her, calling her "my desert flower", dancing around her, asking her to join him in his adventures exploring the galaxy, shielding her from Mr. Potato Head when he sees him as a threat, getting jealous when she hugs Woody, and saving her from not only being pinned under the trash, but from a falling TV set. Jessie first shows signs of strong feelings for Buzz during this rescue, and when he is first thought to have perished after the TV set falls on him, she is clearly in despair. When Buzz returns back to normal, Jessie is overly joyous and relieved that Buzz is alive. However, it is actually during the incinerator scene when they truly realize their feelings for each other. And after the group is rescued, only Buzz and Jessie continue to be holding hands after the claw delivers them all to safety. During the credits of Toy Story 3, the two finally seal their relationship, with Jessie taking the initiative for the two to dance an exciting paso doble.
In Small Fry, when Buzz makes it back to Bonnie's room, Jessie is overjoyed to see Buzz, she rushes over to hug him.
In Toy Story of Terror, Buzz is very protective of Jessie. When she gets locked in the toolbox, he rushes to her rescue, holds her hand once the lid is lifted, and carries her to the safety of the toys' suitcase. He comforts her when she panics, and when the toys pair up to look for clues, the two of them go together. After Jessie is caught by Jonesy, and put in the case with the other toys, she and Buzz share a joyful reunion where they embrace, happy that they're safely back together.
Their relationship isn't shown as much in Toy Story 4, but they are still a couple. When the toys are in Bonnie's closet, Buzz is seen kneeling in front of Jessie, who is having a panic attack in the dark. There are other small moments between them, such as shared looks of concern over Woody ("We're here for you, buddy!") and Jessie leaning with her head on Buzz's shoulder twice when they flop into toy mode in the RV. When the toys come onto the roof of the RV, Buzz takes Jessie's hand as she steps down onto the awning. And as the toys pull away from the carnival after saying goodbye to Woody, Jessie places her hand on Buzz's shoulders, showing that the relationship between the two will continue.
When Buzz first saw Sid torturing a Combat Carl, he was horrified by this cruelty and tried to stop him, but was held back by Bo Peep. When Sid blew up the Combat Carl, Buzz was even more disgusted with Sid's cruelty towards toys. After being won by Sid at Pizza Planet, Buzz was shocked by all of his Sid's deformed toys and was tortured by Sid the next day. After getting a new rocket in the mail, Sid decided to blow up Buzz with it, only to stop when it started raining outside. Once it stopped raining the next day, Sid made way through with his plans to blow up Buzz. However, Buzz was saved when Woody and all of the deformed toys scared Sid, which Buzz watched in amazement.
Buzz and Stinky Pete first meet when Buzz and Andy's toys (along with an Utility Belt Buzz) arrive at Al's Penthouse to rescue Woody. There wasn't any dialogue between the two as Buzz tried to convince Woody to return to Andy, but when Buzz and the rest of Andy's toys left, Stinky Pete was happy and congratulated a depressed Woody. However, when Woody changed his mind and decided to go back to Andy, Stinky Pete blocks the air duct and openly makes fun of Buzz, revealing his hatred of him and space toys in general, as they were the reason Woody's Roundup was canceled.
At the airport, Buzz managed to find Al's suitcase, but when opens it to retrieve Woody, Stinky Pete angrily punches Buzz in the face and sends him off the ramp. Thankfully, Buzz survives and saves Woody from the Prospector, using cameras the other toys found in another suitcase. With Stinky Pete blinded, Buzz reprimands him and doesn't bother to give in to Stinky Pete's angry rants that children destroy toys and how they'll end up in a landfill. Deciding to teach Stinky Pete the true meaning of "playtime," Buzz helps his friends put the Prospector into a little girl's backpack and happily watches Stinky Pete being taken in by his new owner.