Was the general plan amongst nations to simply shoot on sight? Or was he targeted for arrest and trial? I'd assume the Western Allies would aim to capture and trial Hitler, whereas Russia would most likely go for a shoot to kill or death sentence straight off the bat.
Additionally, what kind of punishment would Hitler face if he had been captured before committing suicide? Say, if the British captured him, the Russians captured him or (for some reason) he was captured and trialled by the Americans?
According to this article from The Independent, which is based off of recently declassified notebooks from the British National Archives, Churchill favored execution, in the most hideous way he could find - the electric chair. According to Deputy Cabinet Secretary Sir Norman Brook, who was present in many high level Cabinet meetings during the war (and who compiled the aforementioned notebooks), Churchill's views were as follows:
If Hitler falls into our hands we shall certainly put him to death. [He is] not a sovereign who could be said to be in [the] hands of ministers, like [the] Kaiser.
Further, Churchill did not want to try Hitler at all. He goes on, again according to Brook's notes:
The trial will be a farce ... they [high ranking Nazis] should be treated as outlaws. ... I would take no responsibility for a trial - even though [the] US want to do it.
I can't source anything for the plans of the US or the USSR, and Hitler's fate would have surely depended on who captured him. Given the horrible, horrible things German troops did in Eastern Europe, I'm sure whatever Stalin might have had in store for him would not have been pretty.
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