that is weird, how ova are never included in the greater arcs. I guess it makes dollars and cents.
IIRC the movies were made for annual Shonen Jump events during the 90s.
Each movie is based on stuff that happened in the manga or anime at that point-
The first 2 Dead Zone and World's Strongest could be excluded since they aren't based on anything from what was airing at the time
Tree of Might was based on the enemy Saiyans and on how Raditz was Goku's brother
Lord Slug was based on how the crew were on Namek since the main villain is a Namekian
Cooler's Revenge based on the Freeza saga
Return of Cooler, based on how Freeza was resurrected as cyborg and because it was well into the Androids saga
Super Android 13! self explanatory since it was aired during the Androids saga
Broly this one's....tricky this one aired after Gohan was able to achieve Super Saiyan and the Cell Games had started in the anime. I guess it was inspired by Trunks' failed Super Saiyan form
Bojack Unbound is based on the Cell Games since there's a tourney involved.
Broly - Second Coming, Broly was popular so they brought him back. This was during the Great Saiyaman arc and before the Buu arc started so they didn't have much to work with.
Fusion Reborn Inspired by Buu and Fusion, note that both Goku and Vegeta are dead during this movie
Wrath of the Dragon involved a 'sealed evil in a can' much like Buu was