I would like to point out that Chaos isn't the most advanced, nor are the Triarians. Info on Supremes below.
[hider=Universal Supreme Collective]
Directly, they are, since they are part of the Galactic Community. However, hovering around the edges of society, and generally just being distant and ignored are the Supremes. The Universal Supreme Collective can be random, wise, or strict, depending on what they feel like in that particular part of their year-like cycle. In some cases, they might just show up in orbit of your homeworld, and sit there for a little while before saying hello, and disappearing. At other times, such as during a battle, they'll show up and obliterate anyone who directly stands against them. No one has ever really stood against them, nor have they ever taken much interest.

The USC, Universal Supreme Collective, are made up of a race that is naturally the 'Supreme' race, which are [lightly] radioactive, with a tough hide that seems to make up just about their entire bodies, including their teeth and mouth, due to a genetic disorder that even they couldn't reverse at the end of the Reaper War. They are the first sentient species of the universe, and the only sentient species from the first known sentients to continue survival. In their early years, they wiped out other growing nations and amassed a giant amount of territory, incomprehensible to any of those within the Milky Way Galaxy, or MWG. However, they are mainly a nomadic race, preferring to live within their fleet with numbers that have only recently reached four hundred billion, spread across a great variety of ships, including one giant one that is beyond the current technological levels.

The Supremes, individually, are either their natural species, or they have put their bodies into a dormant state, and inhabit Draconian, Human, a telekinesis-telepathy oriented 4-armed race, and a spider-ish race. They are supremely powerful in both technology and with their minds. Don't attempt to mind-control them. They will swat aside your efforts and crush your own. Ever individual Supreme is practically a demigod. Because they always travel in numbers, a deity can't effectively spy on them, see them, hear them, just as another deity can block access from another deity. This is because there is a bunch of them, not because they are individually powerful enough to rival a god.

However, faced with a 10-to-1 ratio, with them having one or two ships, and the enemy having ten to twenty, it is unlikely that they will battle for very long. They have grown above fighting, in their minds, though that's simply their justification for becoming a bit more cowardly. 

They also genetically-engineered well over a dozen species, ranging from specifically industrial races to specifically warrior races, the most prominent being Draconians. The Draconians ended up bringing about the power to their deity, 'The Goddess,' who also had a bit of part in human life [since Draconians also have human DNA embedded in them], and worshipped the Supremes as something of a Covenent-to-Forerunner people. The Draconians have never encountered any working piece of Supreme technology, nor a live Supreme.

Ya. I'm bored.[/hider]

Should I set up a list of the major Supreme ships as well?