ACROSS THE KICK FIGHTER UNIVERSE
At the time of its publication, Kick Fighter Komiks was one of the few Filipino comic books back then to have its characters explicitly inhabit a shared universe. The first major crossover between its heroes was in its "Winter Special Edition" (must've been an effect of climate change) issue #48 (December 30, 1993).
(Art by Lando Inolino)
Headband guy in bottom right: Hiro
In his own series, Biotrog would occasionally team up with his fellow Kick Fighter stars, such as the wrestler Hugo, with whom he debates the virtues of brains against brawn.
He later joined forces with Kahddim of Kulto to fight off his own demonic doppelganger.
Biotrog also made guest appearances in his co-stars' series. He and Angel went to the beach with Bronco in a 2-part Mysteryo story.
He then teamed-up (or rather, fought with) Kickero the Kick Fighter in a multi-part storyline where they are pitted against each other by their respective arch-foes.
Art by Joseph Caesar Sto. Domingo
When KF was revamped (retitled as Kick Fighter II) with its 118th issue (May 1, 1995), its characters were reshuffled and paired off into new serials. Biotrog would co-star with secret agent Jolas Zuares in a new series called Blades and Bullets.
After a brief hiatus, the magazine was revived anew in 1996 as Kick Fighter III. Biotrog and Jolas returned to action in another new series, Omni Powers, where they are joined by Balzaur of Versus and Nerva of Vengeance.
Kick Fighter III eventually folded in late 1996, but Biotrog co-creator Gilbert Monsanto would not let the character go gently into the night. In 2005, 9 years after his last appearance, the silver-masked cyborg resurfaced in Monsanto's online fan-comic Digmaan, which teamed him with various Filipino comic book heroes such as Darna and Captain Barbell.
In 2006, Monsanto published Rambol Komiks under his independent imprint Sacred Mountain Publications. One-half of this flip-book format anthology magazine ran the series Metropolitan, which brought together many of the characters Monsanto created throughout his career. Among them was Biotrog, but as it turns out, the hero that appeared wasn't really the original version. This was actually his son, Rayden Summers, who had followed in his father's bionic footsteps in the series' future timeline.
As for the original Biotrog, he is slated to return in Biotrog Reassembled, a project tentatively scheduled for 2011.