Once the other trophies have been finished, this will likely be one of the last to unlock. I found a relatively easy way to get 100+ points per fight and win each round in about 5 - 10 seconds on most occasions. Enter Quick Battle and search for an E5 Character called BloodyFrosty. They use the Sigfried character, but more importantly is the stage. It's the level set in the Drawbridge and, by using Astaroths Ax Lower Cannon (away, Triangle+Circle) it is very easy to get ring outs! Way faster than simply doing Arcade over and over, but still is a grind depending on how high you are levelled up when you begin! Sometimes the A.I moved at the start, but it's very easy to beat legit, so no worries.