Play as Big Show and replace every wrestler either with the 70s/80s ones, created wrestlers, or a combination of the two. Set yourself as the Number 1 entry and start the match.
The two easiest methods that I found were to either throw them into a corner and do the quick-time type mini-game or to simply throw them over the ropes and do the button-mash game. (Note that if they are laying down on the apron after you throw them over, that mini-game is significantly harder than the other two)
What I did both to avoid getting bored and to give myself some insurance if I ran in to trouble later on was just wrestle some of them. After about 5-10 wrestlers you should earn one finisher that will remain as long as you don't use it. These are helpful in case you end up in a situation where you are being thrown over and you can simply use the finisher to get out of it. Just to one or two cycles of strong grapples, throw them out, then move on to the next competitor. New wrestlers enter every 30 seconds meaning that this achievement should take about 15 minutes to get.