>>4496923There's GaoGaiGar and GaoGaiGar Final, in that order.
GaoGaiGar Grand Glorious Gathering is just a re-imagined and much worse GaoGaiGar Final, and because it's a TV series unlike the previous OVA series they had to pad it out with flashbacks and connecting it with Betterman to fill the 12 episode quota.
GaoGaiGar's a part of the much larger Brave franchise, but none of them are connected to eachother and exist as separate mecha shows and separate settings/stories/characters.
