Gandalf would still cane. Just think: The most powerful character in HP: Harry Potter VS The most powerful character in LotR: Eru/Illuvatar. There's far more powerful things than Gandalf in LotR, and when compared to the most powerul in HP it simply doesn't compare.
But harry can die and come back to life too! So maybe they're both immortal, and it'll be just like that battel between Jack and Barbossa in PotC one, and they'll be stuck dueling foreverrrrrr. (Huzzah! I just put my three favorite fandoms into the same analogy. )
(even though Rowling said that he never technically "died". Psh.)
harry. avada kedavra is an instant kill spell. gandalf is NOT immortal so he will probably perish. but it's two complete different worlds. it's like comparing the hulk with spiderman..
But there are occassions where Avada Kedavera has been avoided (ie. harry lived through it twice)
Also, even in the Potter universe, there are shield spells, and deflection spells, and things that can be used to avoid the killing curse. I am positive Gandalf has equally useful skills that can help him deflect a curse should the need be there.
How do you know "God" of the Potter-verse isn't on Harry's side? Somebody's obviously looking out for him, considering he's survived the killing curse directly twice, was lucky enough to make priori incantantem (sp) just in the nick of time, with EXPELLIARMUS of all things to save his life then, has fawkes to appear at the right time always to save his life, And everything always happens just exactly perfectly for him when his life is in danger, and is the luckiest person in the entire series. He's probably lucky enough that he could like, fill up a vial of his blood and it would be just as useful as Felix Felicis.
((Please Don't take offence of anything I say here, really. 95% of the stuff I post, in this thread especially, is sarcastic, and should be taken with a grain of salt. I just like to play devil's advocate ))
How do we know who the God of HP is? (if there is even one)
Gandalf is almost as old as the universe (in Tolkiens world obviously) itself, so he also has more wisdom (among other things) than HP has in his little finger. This, undoubtedly would aid him in squishing that runt.
Lol Gandalf is the most powerful one in LOTR becuz no one could defeat the balrog but him and hes the only one that could make the nazguls dissapear and can beat them but in the movie they dont let him use all his powers until he was fighting the balrog when he strikes him with his lightning.And Gandalf can use spells with saying any magical word like HP.So I think Gandalf is much better than HP.LOL!!!!!