Goggle V was the first to introduce creative writing and the idea of ending it with a "V" like how Gogo V was later named. Gogo V sounds to close to Goggle V though they are hardly similar. It also introduced the concept of biologically created monsters.
The Dynamen were the first team to wear spandex. Also it was the first to feature racist villains based on Earth rather than being an alien. Oh yeah this was the first series to have a ninja in the team too!
Bioman introduced the concept of electronic abilities (later used in Megaranger). Also Mika Koizumi despite her early demise made an impact of creating tougher females and I believe Natsumi and Chisato were tributes to her. Bioman had the first humanoid robot assistant. Gear introduced the concept of a mad scientist, a strongman beast and an acrobatic female as villains. In the Bioman movie she had a team that probably inspired the Hanarangers. Natsumi was a rebellious yellow ranger in red and Chisato was a photographer. Also this show hinted that sooner or later, a sixth ranger would come. However Yamamatori (Jun's lover) got his powers from Gear instead. This was also the season where villains started to get more personal and showed a wider dimension of personality.
Changeman introduced more mature concepts into Super Sentai and the idea of mythical creatures later used in Dairanger. It was also the first to introduce an enemy who is way bigger than the rest of the mecha as Bazoo was really a living planet. Also it introduced the first monster-enlarging agent too.
Flashman introduced the concept of a "lost galaxy" which may have also inspired Gingaman. It also introduced some cool sci fi costumes that may have inspired the Gingamen's attires. Who knows- Lee Keflen may as well be Dr. Hinelar's template!
Maskman introduced several concepts like a martial arts based Sentai, the ki to inner power within, secondary robot that kills it pilot (he wrote a similar one in Ohranger) and not to mention tragic love of Takeru and Ial. Oh yeah, there weren't any surnames mentioned for some reason. Still Maskman made itself darker than its predecessors. Oh yeah, it's up for you to decide whether or not a red ranger named Takeru is also his contribution.
Liveman introduced the concept of academics and Sentai in one. It was also focused on revenge and redemption. In some way the formula of starting with three was later used in Hurricanger and the color coding of the first five was added to Go-onger which was a parody Sentai. It also introduced the concept of combining two robots into one.
Turboranger introduced the concept of teenagers with an attitude which was later used in Megaranger, the concept of sealed enemies, car based mecha and the first base robot. Maybe Yamimaru and Kirika do deserve tribute as they were the first anti-hero couple to show up, probably inspiring Rio and Mele. Not surprisingly he was also a secondary writer in Carranger which was apparently inspired by Turboranger.
Fiveman introduced the concept of a family Sentai which was later used for Gogo V and Magiranger, two series better than it. Otherwise this was just where his writing really slowed down. But otherwise the concept left behind something to improve on.
Missed any? Let me know.