Note beforehand: In my writings I will always refer to the fusion between Kaioshin and Kibito as Kaioshin, there is almost no evidence of Kibito in the fusion except from Kaioshin's change in appearance and his increased power.
For those of you who wish to follow the course of Dragonball GT as being part of the other Dragonball series, this article may prove as a surprise to you. It has already been stated that Kaioshin helped save the day by informing the Z Fighters of Buu, thus averting a massive fiasco even worse than what happened regardless.
Between one quarter and one third of the way through the series, the Baby saga begins. I won't go into spoiling one of the coolest stories in all of Dragonball, so I'll get to the point. During the fight with Vegeta-Baby (Baby possesses Vegeta, Vegeta is NOT
cooperating with him!), Goku is nearly killed by Baby's Revenge Death Ball, a powerful gigantic energy ball created to wreak vengeance upon the Saiya-jin, ancestral enemies of Baby's creators, the Tuguls (the original inhabitants of planet Vegeta, also called
the Tsufuru I think). If Kaioshin had not kai-kai-ed into the fight and knocked Goku (accidentally) into another dimension, he would be small dust particles floating about Baby's restored planet Tugul (in orbit around Earth). Goku makes his way out of this other dimension, towing along with him two Space Raccoon Cats (I'll explain later). He is dropped into the middle of an asteroid field somewhere in space, and he is nearly crushed between two of the rocks, but the Supreme Kai's perfect teleportation saves him once again. Let me point out at this time for those of you wondering why Goku just didn't 'Instant Transmission' out of there, here is the reason: he lost the ability when he was turned back into a kid at the start of GT. He only regains the ability after he reaches Super Saiya-jin 4. Speaking of which, it is the Kaioshins who realize Goku's potential to go Super Saiya-jin 4 and go through hellacious effort to extract his tail, which they succeed in doing. Without them, he never would have even thought of doing it. Meanwhile, Baby has planted mind-control eggs into everyone except Uub, Pan, Fat Buu, and Mr. Satan. Kaioshin, seeing this, makes a trip to Kami's lookout in order to steal the Sacred Water (remember the water Kami used to counter-act Garlic Jr.'s Black Water Mist?). Kaioshin sneaks through the palace, searching through different vessels looking for the right water. He is sneaking because both Dende and Popo are possessed as well, and he doesn't want to have to kill them in self-defense. He then goes to Tugul and begins passing out the bottomless amount of Sacred Water which kills Baby's mind-control eggs.
After this and Goku's victory over Baby, it only seems to get worse. The Black Star Dragonballs were used a second time by Baby to create a new Tugul, thus when the first year of their use expired, Earth began to explode (I'll explain the full details of the Black Star Dragonballs later on). Massive chains of people were formed as Kaioshin and Goku (in Super Saiya-jin 4) began to teleport people over to Tugul. Everyone makes it over, but Piccolo sacrifices himself and stays behind so that the Black Star Dragonballs would be
permanently destroyed. Don't mourn for Piccolo, he later on becomes master of Hell and has fun kicking the asses of all the old villains for eternity. After this the Super 17 saga commences, which Kaioshin does not play an active role in.
After this, Goku and the others attempt to summon Shenron to resurrect all of 17's victims (Earth was restored by Porunga after Baby's defeat). When summoned, Shenron is a twisted, hideous version of his former self, the result of over-use which Rou-Dai-Kaioshin had warned Goku of several times before. As Rou-Dai-Kaioshin tells it, each time the Dragonballs are used, negative energy builds up within them, slowly corrupting them. He said that only a few wishes should be made about every one hundred years to give the Dragonballs time to cleanse themselves of the negative energy, but being as they had made so many wishes in just a few decades, and had even made Dende give Shenron an upgrade, they were going to have to pay the price. The seven evil dragons were created from the negative energy, each giving Goku a challenging and unique battle. After the most spectacular battle I have ever seen, the series ends with Shenron riding off into the sunset, Goku in tow.
Kaioshin and all the characters shall live on in our fanfictions for years and decades to come. Something like this isn't just some fad. I hope all of you reading this have enjoyable times writing.