Sero Degajawira is the founder along with Makar Rogonire(Leader One) and Allajakira Fuuja(Leader Two) and code-named Leader 3 of the Gatherers. He claimed to be stronger than SS rank ninja as his every battles in the past, he never show more than 1/20 of his full strength and skills. This claim was yet unconfirmed, but he is the strongest in the Gatherers and in charge of the Gatherers' military branches and power (like general).
Sero Degajawira's techniques and skills:
It is said, according to the Gatherers' member's report, that Sero can be like the 3rd Hokage in prime state, as he can perform many jutsu, includiing kinjutsu, knows and can effectively use many styles of taijutsu, has a perfect chakra control (meaning he can perform many genjutsu, except Tsukuyomi, off course) and incredibly huge chakra reserve/capacity. His strength is, reportly, on par with Tsunade and perhap even far greater than her strength. His speed is said to be fast as one in 8th Gates. He may able to do the 8 Gates as his body is physically bulky and tall (even for human), but unconfirmed. It also mentioned that Sero can take A-rank fire jutsu and walk out as unharmed.
Sero's Supposed Immortality:
According to the Gatherers Research Centers, his blood and age seem to be over 50 or possibly more(?) and contain a number of odd substances that is similar to the supposely a mutated version of bacteria/enzymes that started a first life in ocean. How he came to had it in his system? Nobody knows, not even Sero and Makar. It is possible that his great-great-great grandfather/grandmother may had been with demon or demon himself/herself. His appearance seem to be remain look like 35 years old as possibly caused by Sero's chakra and mutated enzymes altogether. His body seem to has an odd-looking limb on his left hand.
His amount of mutated enzymes or F.A.E.O.C (freezed age enzymes or cells) as Makar called it, caused him to need to take huge amount of life force of living organism monthly, meaning not only he eats cooked, he also eat animals alive and possibly humans or a sacifices as joked by the most sickest mind member/scientist of the Gatherers. In most popular theory of scientists, if Sero don't have a decent amount of life-force from living organisms, his body would probably age greatly and crumble, but it is only a theory. One would ask 'how can Sero 'eat' a life-force out of living beings?', well Sero would perform a forbidden jutsu/ritual that involved mixing his and other's blood together, attaching his odd-looking limb to his victims' body and Sero would had only one hour to eat any living beings alive. Which explained why the Gatherers Main and Minor Bases employees wear a special earmuffs as Sero's sick ritual often had victims' agony screams.