The Avengers are going to win this one, but make no mistake, it'll be one helluva fight! It would take at least 2 or 3 movies before the final outcome & even then it would still end with Godzilla going home!
The lightning thing is King Kong's shtick... Hulk & Thor both have near limitless strength, Black Widow & Hawkeye are good at finding an opponent's weak points & exploiting them, Tony Stark is super intelligent & can devise a solution to almost any situation & Captain America has superhuman abilities. Godzilla's scales give him an increased resistance to most forms of damage, he can absorb all forms of radiation, however it has been seen that if he absorbs too much he goes nuclear, his sheer size alone gives him near limitless strength & endurance & his atomic breath attack is pretty deadly. He is, however, a creature of purpose, rarely appearing without reason & thus the Avengers would eventually discover that reason & aid Godzilla in ending it before sending him home to monster island.
i agree that they would join forces. but let's say he's a evil clone. godzilla can absorb lightening just not man made. so thor is useless aswell. and yes hulk can have a good chance thats only if he's angry enough if not he'll be knocked unconscious. also marvel did a story that godzilla was in and he beat them.