Beast-Fist God SaiDain

Beast-Fist God SaiDain (獣拳神サイダイン, Jūkenshin Saidain) is the Geki Beast of Ken Hisatsu/GekiChopper. It is considerably larger and possesses more brute force than the other GekiBeasts and can also unify sets of Geki Beasts to amplify their attacks. When SaiDain first appeared, it caused a rain of Beast Power Bloom (獣力開花, Jūriki Kaika), which multiplied the energies of those who stayed on the true path of the Beast Fist tenfold, with the Kensei and Kenma excluded from receiving the Beast Power Bloom power increase.

During the Geki-Rin rebellion, the Beast-Fist founder Bruce E was betrayed and murdered by three of his students who would go on to become the Kenma of the Confrontation Beast-Fist Akugata. After the Kenma were defeated and their souls imprisoned within the Kenma Bracelet, Sha-Fu and the other Kensei learned that their master's soul still remained and used the Virtuous Beast Sword to carve a vessel for it out of rock, which would later become SaiDain.

Years later, the Virtuous Beast Sword was entrusted by the Kensei to Ken, only to have it stolen by Mele who gave it to Rio so the two of them could enter Jugenkyo and take Bruce E's power for Rio's use. The Gekirangers and the Kensei followed them and during the battle, Ken was able to reclaim the Virtuous Beast Sword and, with it, also obtained the awakened SaiDain as his personal Geki Beast.

Beast-Fist Giant God SaiDaiOh
In addition to it's beast form, SaiDain can transform into a humanoid version, Beast-Fist Giant God SaiDaiOh (獣拳巨神サイダイオー, Jūken Kyojin Saidaiō), with the call of "Beast-Fist Giant God Descending" (獣拳巨神降臨, Jūken Kyojin Kōrin), or more simply, "Beast-Fist Transformation!" (獣拳変形, Jūken Henkei).

In this form, SaiDain's horn becomes the Smashing Big Sword (砕大剣, Sai Dai Ken) and its back becomes a shield, which is marked by the kanji for "large" (大, Dai).

It has a total of three Fierce Techniques to it's arsenal:
 * The Smashing Great Exploding Connection (砕大爆連, Saidai Bakuren), where SaiDaiOh slams its sword onto the ground, creating a trail of explosions to slam into the target.
 * The Great-Great Smashing Great Slash (大大砕大斬, Dai Dai Sai Dai Giri), SaiDaiOh's signature finisher as a standalone mech, where SaiDaiOh's sword extends, then the mech gives three almighty swings, leaving the "Dai" (大) kanji upon the completion of this technique.
 * The Great Iceflow Mountain (大氷塊山, Dai Hyōkai Zan), where SaiDaiOh spins the sword at insane speeds, sending a blizzard towards the target and freezes it in place.

Herculean Giant SaiDaiGekiFire
SaiDain can combine with GekiGorilla (in GekiFire form) to form the centaurish SaiDaiGekiFire (サイダイゲキファイヤー, Saidai Gekifaiyā), with GekiWolf riding its shoulders and GekiGazelle and GekiPenguin running alongside it. In this form, SaiDaiGekiFire combines the energies of Kageki (the main Gekirangers), Shigeki (GekiViolet), and Geki Hard Kensan (GekiChopper), into its attacks. It's finisher is Fire Smashing Big Assault  (ファイヤー砕大突撃, Faiyā Sai Dai Totsugeki), where SaiDain knocks the opponent into the air with a double slash of its horn where GekiWolf, Penguin, and Gazelle attack it in turn before GekiFire finishes it off with its double swinging fists.

Beast-Fist Giant SaiDaiGekiTohja
GekiTiger (in GekiTohja form) can also combine with SaiDain to form SaiDaiGekiTohja (サイダイゲキトージャ, Saidai Gekitōja), with GekiWolf on its shoulders and GekiCheetah and GekiJaguar running alongside him. It's finisher, Smashing Great Firm-Firm Attack(砕大頑頑撃, Sai Dai Gan Gan Geki), is almost the exact same as SaiDaiGekiFire, only with GekiTohja buffets the enemy with it's Great Firm-Firm Fist attack.

Beast-Fist Giant SaiDaiGekiRinTohja
The final combination of GekiBeasts and RinBeasts as bonds. It used its finishing attack, Smashing Great Fierce-Confrontational Slash (砕大激臨斬, Saidai Geki Rin Zan) to beat Long.