Intelligence...
Leugocyte: Animalistic nornally, Gifted in combat (While normally Leugocyte would be a simple cosmic White Blood Cell, that instinct has been sent into overdrive due to being made berserk by Tregear, causing it to target any planet in its path indiscriminately. However in combat, Leugocyte has been shown capable of dealing with the R/B brothers, including their fusion form of Ruebe which is the accumulation of their capabilities, even holding out the advantage most of the times)
Gilvallis: Extraordinary Genius (Gilvallis is capable of managing the numerous scouts of Galactrons he has sent throughout the multiverse, even accumulating the data they've gathered in their time. Gilvallis would later use those info in his combat form to take on the combined efforts of Geed, Orb and Zero, two of whom are Ultras with at least millennia of experience, and being able to fight off Orb and Geed's strongest forms which combines the fighting styles of their many previous forms that in turn are combinations of their component's skills.)
This is the best I can come up with.
Also, skimmed through RB's finale and it was pretty interesting looking at it in a worldbuilding aspect of sorts. There's now the additional info of Aizen being able to cause space time gates by colliding matter which probably means Katsumi would've resisted that, as the transportation between dimensions can get dangerous if the wormhole isn't a stable one. Which also adds general resistance to space-time to Ultras as well, which now gives extra basis for Zero's resistance to be upgraded.
In addition, Leugocyte should also have resistance to Paralysis as DRLN said his power exceeded their calculations, Aizen's calculations, on a beam made specifically to restrain monsters. Also Status Effect Inducement as one of Orb Dark's targets immediately went inactive, didn't it? So yeah, buncha stuffs.
Ruebe also gets enhanced resistance to Atomic Deconstruction, in addition to Probability Manipulation as Mio was literally in a nigh-omniscient state by being in that imaginary space, where numerous futures were shown, and they brought out the future where they won. But I already mentioned this so whatever. It might also work as Fate and Probability Resistance as well.