From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Super Namekians (スーパー ナメック星人, Sūpā Namekku-seijin; FUNimation "Super Nameks"), Super-Namekians, or Super-Nameks, are a group of ancient Namekians who manage to unlock their abilities and achieve seemingly insurmountable power. With so much power, however, they are more susceptible to corruption. To rid their world of the new villains, the Namekians use Polunga, the Namekian Dragon, to banish them.
After Piccolo fused with Kami, he powered up to levels well beyond that of any existing Namekian. He said that the form was like the Super Saiyan transformation for Saiyans. Kuririn called him a Super Namekian because of his new and extraordinary powers, able to far eclipse the strength of an untrained Super Saiyan.
In Dragon Ball Z: Lord Slug, some extremely powerful Namekians found the ancient secret to unlocking a higher consciousness within and became Super Namekians. These Super Namekians were extremely aggressive and very different from their agrarian counterparts. These Super Namekians also seemed to be able to show off their true power. They were banished from the planet by the other Namkekians by use of the Dragon Balls. The only shown example of such was Slugg.
It is doubtful that Super Namekians were a fundamentally different type of Namekian. Super Namekians, as far as can be discerned, were simply very powerful Namekians and the term Super Namekian was only a nickname.
By the end of the manga, Piccolo was by far the most powerful Namekian, which would make him much more powerful than the Super Namekian Slugg or any of the others that were known of in the series. Piccolo could hold his own and even took the advantage at points in battle against an opponent as powerful as Artificial Human No. 17 during the Androids Saga. As the Cell Games approached, Piccolo decided to enter the Hyperbolic Time Chamber to train. Doing so greatly increased his battle power, as noted by Son Goku and Future Trunks Brief. The argument was that Piccolo fused with two powerful Namekians (Kami and Nail), making him by default the most powerful Namekian. Even without fusing with Nail and only fusing with Kami, Piccolo would still have been much more powerful as noted when Nail stated that if he had been reunited with Kami prior to coming to Planet Namek, he would be more than ready to defeat the same Freeza who had mauled Nail in battle.
Super Namekians were mentioned in Dragon Ball Z: The Legacy of Goku II.
Known Super Namekians
- Nameless Namekian, who later splits into Kami and Piccolo Daimao.
- Piccolo, after fusing with Kami.