Re: How to play against shotguns?
@Mortal-san Use cover, breaking line of sight and increasing the distance between you and the enemy. Movement will help you dodge some shots against less skilled players but is less effective against good players.
You don't want any positioning tips...why? If you want to win a close range fight against a competent person with a shotgun, obviously it's really hard without some solid positioning. If, according to your 3rd scenario, you lose 100% of those encounters, then my serious answer is to either have a shotgun yourself or get a better position to fight this enemy. Sorry if this isn't the answer you're looking for.