I am going to make a division here between mentors and Commanders. A mentor is someone who guides the team and helps them on their mission like Barza from Kyoryu Sentai Zyuranger.
A commander may have given them their powers but also gives them their marching orders. This would be someone like Commander Odagiri from Choujin Sentai Jetman.
I am only going to focus on mentors for this particular ask. Mainly because Aya Odagiri would win for best Commander in a Super Sentai series.
As for mentors, my favorite would have to be Master Kaku from Gosei Sentai Dairanger.
He’s got such an interesting character arc by himself, is pretty much your typical Martial Arts Master and even wears clothes that remind me of Splinter from Teenage Mutant Ninja Turtles. You never see what he does towards the ending coming, even with the occasional hints dropped. It was some great foreshadowing and yet, even at the end, you know he actually cares about the Dairanger team. He’s a great mentor and absolutely my favorite!
My least favorite is Moku from Seijyuu Sentai Gingaman.
Seriously, he’s just a talking tree! Outside of floating heads in jars from a certain American series, I have never seen a more immobile mentor. He just sits there in their base giving out wisdom and advice. If the villains ever found him a carelessly tossed match or three crunchies with an axe could do him in.
Oh and I am also not really fond of Grandpa from Shuriken Sentai Ninninger.
Seriously, he comes across as really goofy at times and others he’s just being a jerk to his grandkids with the express purpose of getting one of them to KILL HIM and take over as the “Last Ninja”. Screw that noise old man.
So, apparently, crucifixion in Super Sentai is a trope going all the way back to the first series, Himitsu Sentai GoRanger. This did not get started with Sentai though as Crucifixion in Toku dates back to at least Ultraseven* in 1967:
Perhaps even more (in)famously is the scene from 1972′s Ultraman Ace where the Ultra Brothers are crucified on the Planet Gologotha as a trap for the new hero.
This scene is actually so famous in the series that it got a scene set release in the Ultra Act toyline from Bandai.
I think this got started because the creator of Ultraman and Ultraseven, Eiji Tsuburaya, was a Catholic who liked to infuse Christian religious imagery into his work. The classic Ultraman specium beam pose is supposed to resemble a cross, the ultimate ward against evil.
The actual meaning of crucifixion was apparently lost and seen as just a means of restraint before an execution. Or maybe the meaning was stripped away and the original intent as an archaic, barbaric form of execution restored.
The Super Sentai series above are (in order of the pictures):
Kaizoku Sentai Gokaiger
Himitsu Sentai GoRanger
Hikari Sentai Maskman
Choujin Sentai Jetman
and then two instances from:
Hyakujyuu Sentai GaoRanger
*The episode of Ultraseven featuring the hero’s crucifixion was accidentally aired (in dubbed form) by TNT in the United States on Easter Sunday, an act that upset several of their viewers considering TNT is based in the Conservative Southern city of Atlanta.
Maria (マリア) and Empress Juuza (女帝ジューザ) next to their concept art from Choujin Sentai Jetman.
I will still never get over Maria’s giant Mushroom Hat, it looks like a massive oversized beret. The thing is so ridiculous and the perfect capper to her weird outfit. That shoulder thing is a work of bizarre art.