I wonder who Nick Fury would be....Diglett?

Magneton as Ultron (I would've preferred Genesect)
Raichu as Thor
Lucario as Iron Man
Spinarak as Black Widow (I would've preferred Ariados to be Black Widow but whatever)
Marowak as Captain America (I would've preferred Gallade)
Pidgey as Hawkeye
Jynx as Scarlet Witch (A recolored Gardevoir would of been nice)
Rapidash as Quicksilver (Rotom would be a good alternative choice)
Porygon as Vision (I would've preferred Mewtwo)
Shiny Machamp as the Hulk

Very nice work, but I think that it would be more ominous in subtext if instead of a ruined Pokemon Center sign, a ruined Cipher HQ sign would hint that Cipher from Pokemon Colosseum/XD created Magnetron as the ultimate Shadow Pokemon.

This is an interesting setup you have here.

Let me see:
Raichu is Thor, Lucario is Iron Man, Machamp is Hulk, I believe Jynx is Scarlet Witch, Spinerak is Black Widow, Pidgey is Hawkeye, I'm guessing Rapidash is supposed to be the Silver Surfer, can't tell who Captain America is supposed to be (it's a toss up between Alakazam and Hypno to me), and no clue who Porygon is supposed to be. And after reading the advertisement on the poster, Magneton is supposed to be Ultron.

It's really good none the less.