Koshimitsu translated this spoiler from our request:
CG Spoiler

☆ Cornelia is captured at the Geass Cult by lelouch, but escapes to Schneizel.

☆ Before Ougi betrays the Order, Diethard takes Viletta hostage and threatens Ougi to continue his job as a vice commandor. This is because Ougi is able to hold all these members of different characteristics together.

☆ Schneizel, who had been collecting info on the Geass, plots against Charles.

☆ The OotBK requests the emperor to liberate Japan in return for turning over Lelouc.

☆ Ougi betrays Lelouch twice. First time it's right after meeting Viletta, but Diethard stops him. The second time is after Schenizel exposing Lelouch's identity, and even Diethard is in doubt, so there's no one to stop him.

☆ Lelouch feels responsible for C.C.'s losing memories. He wears a ring on the ring finger of C.C.'s left hand, and say, "please stay with me". C.C. calls him master (or husband? not sure) and does not leave him.
☆ In sasongugomu (no idea what this is), Asahina died in the nuke attack. His last words become the keywords that made the OotBK's betray Zero.

☆ The Knights find out that Zero was a Britannian prince and think he was using them as playthings. Ougi leads the mutiny to kill Zero.

☆ Suzaku gets to know that Lelouch got his memories back. He confronts Lelouch, and
when Lelocuh confesses that he is the reborn Zero, Schneizel, who had someone follow Suzaku, sends in forces to arrest Lelouch.
☆ Believing Suzaku had tricked him, Lelouch decides to go the path of the demon king.

☆ Nina had put her nuke on Lancelot, thinking it as a "stronger" bomb. When Suzaku uses it during his fight with Lelouch, it blew up Tokyo, killing nearly 10 million people.

☆ Nunnally's survival is unknown. Ashford, being in the outskirts of Tokyo, remains intact.

☆ The emperor wants to connect ruins in all parts of the world to Ragnarok. To destroy the old world through this, and create the new world.

☆ Kallen escapes in the new Guren. In the end she weren't able to stop Lelouch and Suzaku's quarrel. Kallen stands in the crossroads of selection, can't decide whether to betray Zero with all other Black Knights or not. A lie from Lelouch hurts her feelings and she decides to leave him. However, when she's thinking about leaving, Lelouch's last line become the key to express his true feelings to Kallen.

☆ The weakness of Rolo's geass is, it strains his heart. When all of the Black Knights betrayed, he is the only one striving to lead Lelouch to the Shinkirou. Britannia army and OotBK joined hands in the pursue. To stop them, Rolo overuses his geass and dies.

☆ Guilford ends up taking Orange's path.
Mech

☆ Gareth: the prototype for Gawain's mass production. (Like Vincent to Lancelot.) Without Rakshata's technology, the hydron cannon can't function, and is replaced by hydron machine gun. Slash harkens in the form of magic hands. The origin of its name is one of Gawain's younger brothers. Also has rabbit ears. The survivals of the Galston Knights will be riding these.

☆ Percival: Knight of Ten's KMF. Hadron machine gun and drill.

☆ Galahad: Knight of One's KMF. Twice the size of a regular KMF, uses a large sword (Excalibur) which is said to be the most powerful in both defense and offense.

☆ Freya (should be Prayer): Nina's nukes. A few prototypes are made; Lancelot is equipped with one.

☆ Great Britannia: Wakamoto's new flying ship. Made based on Avalon.

☆ Guren with long name: Lloyd modified the captured Guren Aerial Form into this, with his original technology. Combining the intelligence of Rakshata and Lloyd, this is the most powerful KMF in history. It's totally different from previous Gurans. You can feel Lloyd's weird taste from it.

☆ Sutherland Sieg: Enhanced and modified from the Knight Giga Fortress- Siegfried. Feels like the Dendrobium in Gundam 0083: Stardust Memory, with powerful weapons hidden inside. It's even larger than Galahad. The pilot is new Jeremiah. The color of its booster is also orange, like Siegfried. Maybe it's this one.