Be ready to tech throws, do not be fooled by Ragna running towards you he can easily stop to throw you when you Counter anticipating a attack. If you can time it, 2D works wonders against his 6C and 2D as well as his other lows. A bad player will fall prey to your counters but smart ones will mix up their attack with throws. I stress even more that teching throws is valuable here as both ground and air throw will take you to the corner where either Ragna's long combos will get you or a mixup to extend his damage. I want to say 6B is overhead but I haven't seen a Ragna use it outside of a combos when I play them. If they run use 4C to stop their momentum. I'm not sure how strong Ragna's air game but players seem to avoid air approaches but if you approach from the air be wary of his fatal counters in 2C and I want to say D as well. But I am most likely wrong on the second one. Please if I got something wrong let me know! But last words tech throws (better yet use them when you can) and 2D help a lot.