The Dragonzord was the personal Zord of the Green Ranger. Whether it was created by Zordon or Rita Repulsa remains unknown, but it was originally on Rita's side when she gifted her Dragon Power Coin to Tommy Oliver, turning him into her own personal Power Ranger, the Green Ranger.
When Tommy later defected from Rita's side and joined Zordon and the Power Rangers, he continued to use the Dragonzord in battle, until his powers began to drain away thanks to Lord Zedd and the green candle. He transferred the Green Ranger powers and thus control of the Dragonzord to Jason, the Red Ranger, before going on something of a wilderness sabbatical. When Tommy returned to active Ranger duty as the White Ranger, he was equipped with a new personal Zord, in the form of the White Tigerzord, which would later clash with the Dragonzord as it was controlled by a clone of the Green Ranger whom Rita had created. In the aftermath of the battle, the Dragonzord returned to its home at the bottom of the ocean. It has not been seen since.
Standing at the same height as the Megazord the Dragonzord can easily hold its own in battle. It is equipped with fingertip missiles, much like Mechagodzilla, who it greatly resembles, and a long prehensile tail with a drill tip at the end. Most notably, it can easily combine with the Megazord, forming the Mega-Dragonzord (which in turn can combine with Titanus to form the Ultrazord) as well as combining with the Mastodon, Triceratops and Sabre-Toothed Tiger Zords to form Dragonzord Battle Mode. It can be controlled in two ways: Tommy or Jason directing it from outside with the Dragon Dagger, or by entering the cockpit and operating it directly, making it much more efficient in battle.