4 Week Continuous Special Super Sentai Strongest Battle!! (2019)

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.

A Japanese tokusatsu television miniseries (crossover special) based on the Toei's long-running Super Sentai metaseries featuring cast members from past installments and acts as a prelude to the events of Kishiryu Sentai Ryusoulger. Following the finale of Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger

It's the 42th sequel of the series from Super Sentai right after Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger which is the 41th sequel. If you would like to watch the super sentai series chronologically.