I've never even heard of "Psycho" or "Destroy" gundams. plus. you just listed two names, even i did that. most gundams, like the orriginal ones, or the 5 from wing, or the SEED gundams, aren't as big as the Eva's from my recollection. but even i know that there are SOME gigantic gundams out there.
to me the shows are too different to compare. + the size difference. Gundams are what like 50ft and the Evas are like as big as buildings.
I'd put my money on Unit 01.
Disregarding a pilot (because I haven't seen anyone mention that Shinji has to be the pilot [meaning that someone wouldn't have to necessarily be piloting it hypothetically]), I think that Unit 01 is practically invincible--not only because of its AT field, but because its apparent ability to continue fighting, power cable or no power cable. When you take the pilot from the equation, Unit 01 seems to be extremely efficient in killing whatever it wants to.
As far as size goes, I think it's pretty irrelevant. If one of them has an apparently impenetrable 'force-field' (yet again, not considering the pilot, since the pilot may falter in concentration and thus weaken his/her field) then I don't think size would matter much.
well sorry to say this to you people but if anyone of you played the super robot wars alpha series, it's actually the gundams that are far more superior to any evas. not saying this because i'm a gundam fan, but again this happened in a game's storyline. one particular gundam is capable of destroying eva with or without a pilot, this gundam is called the turna a gundam. according to the game's story, the turn a was made in the post apocalyptic far future to destroy and beat any earth robots. even in the anime, the turn a did destroyed earth's civilization in a single day with a single attack only at 5% of it's power. though most of you will say that's only a game, but this game is the only actual proof that you get to see mecha crossovers.
by the way, that's just real robots (gundams) alone, there's still hybrids (like eva), and super robots that are far more powerful than eva that i know of.
devil gundam....size? the entire country of japan.
Evangelion 01 in Supergod mode wins. He got the power to destroy everything only with his wish, so any robot can't compete with that. Only a Lance Of Longinus can stop him, but only Eva's can use the Lance Of Longinus, so the other robots can do nothing.
Oh, and by the way, since Evangelion in god mode is a super angel, he can probably change his size at his will just like Rei/Lilith does.
I'm pretty sure thats bigger than Japan.