Given a chord progression in the key of E minor, the relative minor of G, one could use a G diatonic harmonica to solo over the chord progression, yes? I know this probably is not the correct forum for this question, but I don't remember seeing any forums labeled "Music Theory"
The notes are the same, just have to start on E and make that your root

Also there is the musician talk forum :P
Yes, that would be fine. The only thing you should watch is to try and start on an E while using the harmonica for melody. Starting on a G would give the odd effect of starting on the 3rd of the key, which isn't very common if a harmonica is playing over top of a harmony.
They say the old woman's got the wisdom
'Cause she couldn't read the clock anymore
She said "The numbers don't represent the moments"
Says she don't see what all the ticking's for
yeah but absolutely anything goes realy. Would sound weird if you don't start and resolve at the E though
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Yes, that would be fine provided that the progression is also mostly or completely diatonic. You don't need to start on E, you can start wherever the hell you'd like because the harmony already implies E minor and you'd have to try pretty hard to mess that up with a harmonica in the same key :P
i don't know why i feel so dry