Ressha Sentai ToQger (2014)

Both have the same colors for the core team (Red, Yellow, Green, Blue, Pink) and ToQ 6ou is orange while Kiramai Silver is accented heavily with orange.

Both teams are said to shine (Kiramagers shine because their motif is gemstones while ToQgers shine because one of their motifs is rainbows/light) due to the power of imagination. (which is called Kiramentality in Kiramager). Imagination/Kiramentality power their weapons and mecha and the red of each team has the biggest amount of it.

Both teams started with the other four core rangers and have red added in the first episode to the team with the sixth ranger added later on. The sixth ranger is hesitant to join but quickly comes around.

The Mechas are vehicles for both teams. (ToQgers only have trains as their mech while Kiramagers have an assortment of different type of vehicles, including trains)

Both Villians groups want to harness dark from people.

Both use imagination to power up their vehicles (Kiramentality)

Trains are used as mecha (by the villain in Kiramager)

Both aren't well written, sorry I had to say it hahaha

Both are train themed shows that are rather lighthearted and both are by the same writer.

It's the 37th sequel of the series from Super Sentai right after Zyuden Sentai Kyoryuger which is the 36th sequel. If you would like to watch the super sentai series chronologically.

It's the 38th sequel of the series from Super Sentai right after Ressha Sentai ToQger which is the 37th sequel. If you would like to watch the super sentai series chronologically.

Both feature rangers that were kidnapped as kids
Both grew up to become rangers to fight their captures
Both have same color pallet(except for orange and purple) team
Both were later followed up by a "Asian Theme" series
Both feature a humanoid main villain

The red ranger of Ressha Sentai ToQger has an appearance in Bakuage Sentai Boonboomger, so you might want to watch that season prior Boonboomger to appreciate his appearance more.

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.