Super Mega Baseball 4

Start an exhibition game as the home team at Ego 0 and set Innings to 1. Also set the extra innings rule to have a runner start on 2nd base in case you don't win in the bottom of the 1st. Each game should take less than 5 minutes to win with a walkoff hit in the bottom of the 1st inning, or slightly longer in case you go into the 2nd inning. If you're starting from scratch you'll need to keep track of each stadium you win in.

Used this method after playing 3+ long seasons of Franchise mode with standard team home park settings. Had 2 stadiums left from the opposing league to win in, can be easy to miss a few as you'll only play 1 game per season at the opposing league stadiums with standard long season settings. Had to guess which parks I was missing as I hadn't kept track, but went for this achievement near the end of the current season I was playing and used the franchise schedule tracker to figure out which team's parks I had won in during that season and narrowed down my list. Took about 5 games to correctly guess the remaining 2 stadiums I had left to win in.