Be nice, Tero. This thread is about discussing the Sonic Matchups, not bash on the Blue Blur himself.
Any idea how to play against Mario in 2.6?
The biggest issue for me when playing a good Mario is his Fireball cancels into more fireballs and that pretty much keeps my options limited down to just blocking or jumping over and doing a baiteable/punishable home attack. It seems like I have no way around it.
Now, for your question about Mario. I do have plenty of experience playing as Mario as he is my best main in Project M at the moment. The Fireballs do have the potential of zoning out Sonic and coerce him to go somewhere that Mario wants him to be in. Another thing that Mario can do better now with his Fireballs is approaching, especially for Grabs. Mario has always been a combo machine and Sonic is a bit hard-pressed dealing with a smart Mario that knows to not leave himself too open for Sonic's DD+WD movement. He is very capable of dealing with pressure himself and his attacks like DSmash and FSmash have more deceptive range along with less endlag than Sonic's DSmash or FSmash. (Which is kinda suspicious for somebody who is the fastest thing alive.) Dair is one of the attacks to really watch out for Mario as it has great priority that I'm not even sure if Sonic's Fair or Bair can beat which are Sonic's highest priority moves and it can give him breathing room from Sonic's approaches if used right.
Also, getting back onto the stage is a nightmare when Mario is at the edge and ready to guard. It is highly recommended to either recover high or low enough to snap the ledge even if he uses the Cape to turn you around when you use Up B. The Cape is not his only edgeguarding tool, but it is his most safe and deadly trick for edgeguarding Sonic.
While Mario is good at covering his areas against Sonic, Sonic does have his incredible speed to get in on Mario when he makes a mistake and is quite capable of doing combos himself. The best thing to do against Mario is just to keep moving and keep him guessing. Don't let him get you cornered and force you to back up from his Fireballs. Stages that aren't small like Battlefield or Try making Mario recover low so that he is forced to utilize his amazing double Up B recovery. Once he tries to do that, you're free to hit him with your Spring to try knocking him away during the small window when he wall jumps out of the first Up B or try to stage spike him with a quick Homing Attack since HA now sends enemies at an upward angle. (although I'd be careful with that one as not all Mario players will allow you to gimp them that easily as they can still attack quickly with an Upair to knock you away and then recover safely with an Up B.)
Overall, the best thing that I can say about fighting against Mario is just keep mixing up your options and work on Perfect Shielding/Power Shielding his Fireballs as doing that will hurt Mario's approach game. Once he has your movement and style figured out, Sonic doesn't stand a chance against Mario. I know that is something that should be true for Sonic against the rest of the cast, but I feel this is especially true for Mario vs Sonic matchup. While Sonic is fast and capable of pulling off combos, Mario has better priority, range, capable of using Fireballs in approaching as well as zoning, and not to mention much better killing power. In this Matchup, I think that the matchup difference is... 60
- 40
. It all depends on how you bring the fight to Mario with Sonic.
I hope this helps you understand fighting Mario better if only a little.