Movie 1: Digimon Adventure
"Two children receive a strange egg through their computer, which hatches into their very first Digimon, leading to the night that would change their lives forever." (Digimon Wiki)
Sora isn't shown as much as Tai is. She lived in Hikarigaoka as the others from the DigiDestined group did. They didn't know each other, just Sora and Tai did (I assume). She observed the fight between Parrotmon and Greymon just like all the children there. She was in her room cheering for Greymon (how did they all know that Greymon is a good Digimon?). When Tai whistled with Kari's whistle Sora saw him.
I don't know if Sora and Tai know each other but it looked like Sora recognized him - in season 1 they say that they were classmates when they were still in Hikarigaoka. In season 1 they said that this accident happened 4 years ago - it means that Tai and Sora were both 7 years old and to be in the second grade you have to be 7 years old. So probably they really knew each other at that time.
Movie 2: Our War Game
"When a deadly virus Digimon causes mass havoc on the Internet, it's left up to just a few of the DigiDestined to stop him, and save Tokyo from an incoming missile attack." (Digimon Wiki)
In the beginning we can see Sora walking in Odaiba. She stopped at the mirror and fixed her hair. Because she was in a fight with Tai she isn't shown that much. Tai bought her a hairclip and she asked him if he didn't like her hat and they started to argue because of that (he bought her a present on her birthday). In the beginning Tai wrote an email to her but she didn't get it because of Diablomon.
When Tai and Izzy needed help they called all the DigiDestined for help. When Izzy called Sora (Tai didn't want to) her mother was on the phone. Sora just came home and when she heard that someone from Tai's home is calling she said to her mother to lie for her and to tell him that she isn't at home. Later Sora came to Tai's front door. She wanted to ring the bell but she decided not to and she went home. In the end Sora get Tai's email and she smiled and send him an apology mail. We can see her with a hairclip on her hair at the end of the movie.
Movie 3: Hurricane Touchdown
"The DigiDestined kids discover another one of their kind living in the United States, who's own Digimon falls victim to a powerful computer virus." (Digimon Wiki)
At the beginning of the movie, we can see Sora doing some flower arrangement. She isn't really happy with the positions of flowers she made. We can also see that she put her digivice in one of her floral designs. After that she was kidnapped by Wendigomon who took her to another dimension. There she met with her old friends - DigiDestined. They were all really tired there and when Wendigomon fight they could feel it - when Flamedramon attacked Wendigomon with fire DigiDestined could see a red light made from fire. Wendigomon brought them there because he was trying to find Wallace who lost him when he was still a child. As all the rest we can see Sora in her season 1 clothes and later as a 7 years old girl. This dimension looked like a whole new world made by Wendigomon's memories. Sora and the others were saved by Davis and his new DigiDestined group.
Movie 4: Diaboromon Strikes Back
"Diaboromon makes a return to the net, and the DigiDestined are quick to act, unaware that Diaboromon has a couple more tricks up his sleeve since their last encounter." (Digimon Wiki)
Sora wasn't with DigiDestined from the beginning. She was on a trip with her Tennis club. In the beginning we can see a picture of her with Matt - a few pictures were circling the internet and this was one of them. When Kuramons attacked real-world Sora is shown on a train station. Because of Kuramons the trains weren't driving. So she had to wait a little bit longer there. When Tai and Matt were really sad because of Omnion (because he couldn't defeat Diablomon and because of its condition) Sora came to them and she told them to get themselves together and not to lose hope. I think they were really happy to see her. When Diablomon was defeated we can see her smiling along with Tai and Matt. And in the end, there is a picture of Tai, her and Matt.