After this mission you go back to the "home world", Earth.
This is by far my favorite mission. Why? Because you get to use the awesome Hyaku Shiki mobile suit piloted by none other than Char Aznable!!!
Before you get to the Close Range battle so you can use the Hyaku Shiki you have to deal with a few things first. First 3 squads of 3 Hi-Zacks each challenge you and should quickly meet their demise.
Then, 3 squads of 3 Marasais each attack you. You have 3 more squads of 3 Hi-Zacks and 3 squads of 3 Marasais left before the final battle of the Long Range portion and it's gonna be a doozy.
Yazan's back and this time he's brought two buddies with him, Ramsus and Dungel. This is a very easy battle at high levels. All you have to do is wait patiently for your turn while dodging blasts and then let the suckers taste H-M Launcher!!
The Spider Attack is these three's trademark move (similar to the Black Tri-Stars' Jet-Stream Attack). First, all three suits will line up in a row and then fly towards you forming a triangle around you. You remember that electric wire that Yazan used on you during the Mission 17? The three Hambrabis connect their wires together (it appears they do anyway) to form a web that you're caught in that suck AP from you until you break free.
Hopefully one of them will change into its mobile armor mode because your attacks deal almost 2x as much damage as it normally would. Don't worry about their increased speed, the Zeta Gundam should be able to catch up to it without a problem.
The Hyaku Shiki is by far THE coolest mobile suit in the game (and anime for that matter). It looks cool, it's powerful, and Char pilots it! The Hyaku Shiki is extremly powerful therefore dealing with the Hi-Zacks and Marasais will be no problem with both the Zeta Gundam and the Hyaku Shiki.
Once all of the enemy units are disposed of two more of which ever type you killed last will fly in. Destroying these two causes Kamiyuh to fly off to face Yazan, Ramsus, and Dungel.
You'ld think that this would be an extremly difficult battle, but it isn't so don't worry about it. Take out Ramsus and Dungel first. Once Yazan is left alone you can use the same methods you did in the previous mission to defeat him.
In the scenes following the battle you'll see Yazan getting the upperhand on Char and knock him and his Hyaku Shiki into the Earth's atmosphere. Kamiyuh switches the Zeta Gundam to Wave Rider mode and quickly hurries off to save Char (which you probably could've guessed) and succeeds in doing so.