Bakuryuu Sentai Abaranger (2003)

It's the 26th sequel of the series from Super Sentai right after Ninpuu Sentai Hurricaneger which is the 25th sequel. If you would like to watch the super sentai series chronologically.

It's the 27th sequel of the series from Super Sentai right after Bakuryuu Sentai Abaranger which is the 26th sequel. If you would like to watch the super sentai series chronologically.

Both Dinosaur theme Super Sentai
Both have a "evil 6th ranger"
Both were in a crossover with Kyoryuger
Both feature a Red Tyrannosaurus Rex and Blue Triceratops

Both feature a team color (red, blue, yellow, black, white)
Both have dimensional villains with monsters mixed with items and animals
Both have ranger girlfriends that turned evil

It's the very first Super Sentai series what made many of it's successors possible. If you want to watch the original first season of the Super Sentai series.

Both shows are done by the same main writer Naruhisa Arakawa. The show's red ranger personality and philosophical views are similar to Kuuga's protagonist Yuusuke Godai. In both shows most problems get resolved creatively rather than overly relying on the toys that the shows are promoting. At a certain point in Abaranger, a main villain who plays psychotic games against the heroes is introduced which has superficial similitudes to the Gurongi in Kuuga.