By suggesting "easy" characters I was really getting at those with a basic playstyle: that way, at least the top tier characters will be fighting on turf that everybody can compete on. Fighting Ragna is just a contest of footsies, something even Tager can do. Compare that to Tao, Hazama, and Valk, who have special playstyles that let them just fly around him.
The other way to go would be characters that by definition have a weak spot, like zoners.