Allelujah/Hallelujah is my favorite character in Gundam OO, he is REALLY good. Arios Archer even better, the top two Super Soldiers together ( Marie still had Soma's abilities ). Allelujah/Hallelujah is slightly better than Marie/Soma. I however thinks that Athrun is the best. He got beat by Kira Yamato in the Savior was beacuse Callgalli was on the battlefield and was crying and he couldn't really concentrate, he didn't use SEED. Athrun is UNDEFEATED in SEED Mode.
My favorites are: Gundam Meisters ( which includes Graham Acre and Marie Parfacy ), Kira Yamato, Shinn Asuka, Rau La Creuset, Rey Za Burrel, Athrun Zala, Yzak Joule, Dearaka Elsmen, Mu La Flaga, Heeryo Yuy, Duo Maxwell, Quatre Raberba Winner Millardo Peacecraft, Amuro Ray, Char Anzble, Alto Saratome, Ozma Lee, Mikhail "Michael/Michel" Blanc, Luca Angelloni, Shin Kudo, Roy Focker, Kallen Stradfelt, C.C., Lelouch vi Britannia, Cornelia li Britannia, Bismarck Waldstein, Gino Weinberg, Anya Alstreim, Jeremiah Gottwald, Villeta Nu, Li Xingke, Suzaku Kururugi, Kurz Weber, Melissa Mao, Gauron, and Sousuke Sagara. Wait, did I just list every single awesome mech pilot?
Oh yeah, I forgot about them I was frantically trying to think of pilots from Gundam SEED/Destiny, Gundam Wing, Mobile Suit Gundam, Gundam OO, Code Geass, Code Geass R2, FMP, FMP Fumoffu, and FMP: The Second Raid. But the ones I listed are my favorites.
That's all true, but compared to Allelujah/Hallelujah who was fighting against two aces with a mobile suit that didn't have all four limbs, and the fact that Athrun gets owned by everyone unless he is in SEED mode says a lot, and I don't like the way he keeps going on about peace and switching sides inn war.
Athrun doesn't kill people and he fights nobly, anyways he owned everyone at least once. He owned Shinn even when Shinn is in SEED and he was not, and he would have killed Kira if the Aegsis didn't run out of power. Yeah Allelujah/Hallelujah was awesome, he is slightly better then Soma/Marie. Athrun is like a totally different person in SEED, but he doesn't use it a lot ( he is also an AWESOME sharpshooter ). He can beat anyone easily with SEED Mode. The reason he doesn't use SEED a lot maybe because he wants to fight fair? Perhaps he doesn't want to go berserk? Anyways, I also hate how he deserted ZAFT twice.
Then you need to take a look at Trans-arm, SEED and Super Soldiers, they are awesome. If Allelujah/Hallelujah had SEED and Soma/Marie helping then he could beat every mech pilot there is, no matter how good the mech is.
Perhaps, SEED greatly amplifies ones own power, and Trans-arm amplifies the suits power. Allelujah and Marie are both Super Soldiers with enhanced with genetic modifications and nano-machines, capable of communicating using quantum waves and sensing one's thoughts.
But you've seen what Epyon does. It makes it to where victory is so important that the pilot doesn't even fear death. But then again all iv'e ever seen is wing. I think I need to watch more shows.