Isoginjaguar

Isoginjaguar (voiced by Mahito Tsujimura) is a sea anemone/jaguar monster created by Gel-Shocker.

Yosuke Katsurajo (桂木良助 Katsurajō Yosuke), father of Maki Katsurajo (桂木マキ Katsurajō Maki), is captured by Gel-Shocker and transformed by them into the monster Isoginjaguar. Unlike most Gel-Shocker monsters, he is actively remote controlled by General Black, while suffering immensely due to the control. After being defeated by Kamen Rider 1's Rider Point Kick, he sees his daughter Maki calling him and reverts to human form, regaining his memories and control over his own self.

A second Isoginhaguar was part of Dai-Shocker during the "Super Hero Taisen" incident. It's visually similar to the original, but sports Gel-Shocker's standard yellow boots unlike it. Dai-Shocker was led by Tsukasa Kadoya/Kamen Rider Decade, rivaling Captain Marvelous/Gokai Red and Dai-Zangyack. However, Rider Hunter Silva of Dai-Zangyack and Doktor G of Dai-Shocker overthrew their respective leaders and joined forces to destroy the Kamen Riders and Super Sentai, facing off against their combined forces.

In the final battle, Isoginjaguar was seen in several scenes fighting many riders and sentai members, specifically MegaBlack, TimeGreen, ShishiRanger, Battle France, Kamen Rider Black RX, and Kamen Rider J. Isoginjaguar was killed by Kamen Rider OOO's finishing attack with his Medajaribur, the OOO Bash, alongside Hades Wise God Dagon, Scorpion Man, and Ghoster.

Powers and Abilities
Isoginjaguar is able to move swiftly underwater, bite through rocks, use the tentacles on his neck and mouth to strangle opponents, and teleport.

It's also able to launch a powerful Poisonous Water from his back that can melt human flesh.