The Gundam Mark II has the easiest scenario to complete, I suggest you take this if you feel you're not quite up to the challenge of tangling with the others.
Unlike the other two scenarios, this time you'll see an up close look of the conversation between Kamiyuh, Char, and Emma instead of the little sprites with dialouge. Emma in the MK II flies off to find Reccoa and get revenge for the people she abandoned and killed.
The enemy units that you have to face in this mission are ridiculously easy. The Gundam MK II will easily deal 200AP+ damage and they'll only be taking 5-10AP away from you per turn. On some rare occassions you might fight one or two mobile suit that can actually put up a fair challenge but not enough of one to survive your attacks.
Eliminating all of the enemies in all nine mission areas will allow you to move on to the final battle with Reccoa. Reccoa is piloting the Pallas Athene, which, at the beginning of the battle will launch off eight projectiles. Every so often the Pallas Athene will fly off and one of those projectiles (missles) will come down and hit you causing you to be knocked back four spaces and lose 150AP.
You have no choice in this battle except to attack head on with your Beam Saber, unless of course you only want to do 5AP or less damage to the Pallas Athene. Hopefully you brought more Energy-Pacs instead of those useless Gun Magazines.
Despite being the easiest scenario you still will have a fairly difficult time with the Pallas Athene. Its attacks deal 200AP+ damage per hit and that sometimes even more. You'll need to attack while keeping a very close eye on your AP so you don't die before you can destroy the Pallas Athene. To win and beat the game inflict 3000AP damage with your Beam Saber. Too bad Emma also has the shortest ending sequence...