Angolmois energy is the life-force of Unicron. It is a powerful energy source which oftentimes has completely random and unpredictable effects on the things it comes in contact with. It can upgrade a Transformer and give them new bodies, or it can lift mountains and freeze planets.
Just like Unicron, Angolmois is extremely chaotic.
Japanese cartoon continuity
The Transformers cartoon
When Unicron's body exploded, the Angolmois energy (that green electric-stuff) was sent hurtling through time and space.
Kiss Play Position
Believing that they were collecting fragments of the Allspark for the Sparkbots, who claimed to be allies of Primus, the Kiss Players Marissa, Atari and Shao Shao were actually assembling Unicron's dispersed Angolmois energy - which was, for some reason, stored inside famous Autobot leaders of the past, present and future. Fleeing through space and time to prehistoric Earth, the Sparkbots used the energy to resurrect Unicron...who was blown back into Angolmois energy by Primus shortly thereafter.
Primus trapped the energy deep within the planet and created Fortress Maximus to guard it for eternity. Unfortunately, he left Earth with the Kiss Players around 2007, and therefore wasn't on-duty when Lio Convoy and Galvatron came around.
Beast Wars II
In the distant future, Earth turned into Gaea. Angolmois was riddled into the planet's surface and began to have bizarre effects on the environment.
During a space battle with Galvatron and his Predacons, Lio Convoy and the Maximals landed on Gaea after going through transwarp space. Realizing the destructive potential of Angolmois, Galvatron made it his goal to steal all of it from Gaea.
The Angolmois affected the Transformers on Gaea in many ways, including upgrading Megastorm, Starscream and BB, to name a few. Galvatron eventually sucked all the Angolmois from the planet using his battleship, the Nemesis. After a fierce battle which resulted in the death of Galvatron, the Maximals being trapped in a wormhole and the Predacons being set adrift into deep space, all the Angolmois energy aboard the Nemesis was sealed away in capsules and ejected into outer space.
Beast Wars Neo anime
The Maximal Elders, unaware of the fate of Lio Convoy, ordered Big Convoy and his Maximal new recruits to investigate Gaea and see what was up. Unknown to Big Convoy, he was followed by Magmatron and his Predacons. After finding Lio Convoy's black box, they learned about the Angolmois capsules and immediately set off to reclaim them.
The Maximals and Predacons then raced to secure as many capsules as they could. The Angolmois capsules were wreaking havoc all over the galaxy, causing great destruction on the planets they wound up on.
Eventually, between the Maximals and the Predacons, all the Angolmois capsules were recovered. Then, the mysterious and insanely powerful Blendtrons showed up, beat the mortal crap out of both factions and stole all the Angolmois capsules.
As it turns out, the Blendtrons were creations of Unicron. They released all the Angolmois energy into the corpse of Galvatron, resurrecting Unicron. Unicron then attacked Cybertron and possessed Vector Sigma, turning the planet into his new body. Only by teaming up were Magmatron and Big Convoy able to defeat Unicron and save Cybertron.
Beast Wars Neo manga
The Angolmois energy released by Nemesis created whole races of animal Transformers out of organic animals it happened to land near. Big Convoy and all of Magmatron's main troops (Sling, Saberback, etc...) are members of these Angolmois-created species.
Both Maximals and Predacons are told there are seven Angolmois energy capsules scattered across the galaxy in total. What's more, Big Convoy and Magmatron are identified as the last Angolmois energy capsule. Thus makes Unicron wants to eat them.
IDW Beast Wars comics
Shokaract was infected with Angolmois stellar-cycles ago and lay dormant as the energy transformed him. His will overrode the Unicronian dominance, as least temporarily. Some time later, Elephorca, Drancron and Rartorata began collecting Angolmois as an offering to Shokaract, who believed it would cause his ascension and didn't realise the power was making him a mere pawn of Unicron.
After several incidents of civil unrest came to the fore, Big Convoy implied that Angolmois might very well be the cause of the riots, as it had seemingly become an addictive drug to Cybertronians. Big Convoy and the Maximal Elders were familiar with Angolmois and its addictive, unpredictable effects on Cybertronians. This is presumably due to a parallel of Beast Wars II and Beast Wars Neo occurring in this timeline. Angolmois's mutagenic properties became all the more terrifying when Razorbeast was infected by Rartorata, and became a feral berserker.
Eventually, Shokaract's minions began spreading Angolmois to the Cybertronian populace and causing large-scale riots, which empowered an "Anti-Matrix" that he had created. Eventually Bump developed an anti-Angolmois retrovirus and Shokaract killed himself on the discovery he was Unicron's pawn, ending the Angolmois threat.
The word "Angolmois" is apparently taken from the writings of Nostradamus — specifically, from Century X, Quatrain 72 of his Prophecies. In this stanza, Nostradamus uses a sort of "Pig-Latin-French" to refer to the Mongols (which would normally be Mongolois in French) as the Angolmois ("Ahn-gol-mwa" for the French-impaired). Hence the energy being called Angols ("Ahn-jols" as it is pronounced) in the English Fan Dubs of both Neo and II.
There seems to be a fair level of fascination with Nostradamus and his prophecies in Japanese pop culture. The use of the term "Angolmois" here is just one example of its occurrences in anime, much less Japanese pop culture in general.