The Story Of The Star Seekers And Thundertron

The Star Seekers are a faction of transformers not affiliated with the Autobots or Decepticons,but this is rather a faction of space pirates (An example is Beast Wars II) similar to those from legends but more like those from Assassin's Creed 4 Black Flag. 
they were planned at the end of Season 3 and to be the main villains of Season 4. Among them was Thundertron who was rumored and almost appeared in the TFP show before the show's cancellation. 
Ages ago,Thundertron swore that the creatures that causes the destruction of his world would
pay for their crimes. Since then,he has wandered space in search of
his revenge. His ship is primed,his crew is willing and at long last,Cybertron is in his sights.
He vows to hunt down and slaughter any who come from Cybertron and is equally brutal with anyone else who would get in his way. Sensing the energy trail of a Cybertronian ship,Thundertron had his ship land on Velocitron. He quickly questioned the planet's leader if there were any Cybertronian there. Her answer made Thundertron lose his temper and ordered his crew to attack.
Following the energy trail,they travel through a spacebridge to Junkion,where he found not only the Cybetronians ship but another. While the Cybertronians were fighting each other,Thundertron met the leader of the locals. He had two crew members shows the Junkions they meant business by killing one of them. As soon the Spacebridge was attacked,he ordered the Star Seekers to attack the Cybertronians. Some time after the battle on Junkion,Thundertron and the Star Seekers engineered a ruse to trap the Decepticons and to wipe out the Nemesis with the Requiem Blaster. Megatron and the pirate leader came to a stalement  in hand to hand combat while the Nemesis overwhelmed the tidal wave,forcing the pirates to retreat.
Optimus Prime and the Earth Protection Taskforce unsuccessfully attempted to capture Starquest and Thundertron.