I disagree with the main tactic with mario is to spam fireballs.
They're range is wavy and medium. Which at the beginning of a match, If the mario player is doing that, he's very stupid. Spamming fireballs, leaves you at the same place as you started, close to an edge. Playing mario, I have always found his dash a great distance eater. If one player is foolish enough to rush you, use fireballs, then dash attack +SH Nair.
But if they are campy, cape one of the projectiles, SH, land and dash attack.
Mario cannot return fire very well, characters that have long range projectiles will tear him to pieces if he doesn't move.
My mario is a very aerial mario. I use his dash to pop them in the air, Upsmash to keep them there, and Uair to the star KO. This play style is uncommon. Most other mario users like to remain grounded. This then becomes a very campy mario, and throws fireballs at the darkness, which don't do anything.
A good mario will move around, and get in your face, a unsuccessful one will Neutral B to his or hers hearths desire.
Also, Mario's down B is another thing to take note of. It doesn't do damage. But fully charged, it makes him heavier. Meaning he travels less from a lucario Fsmash then he normally would. Less travel distance, easier to save himself. He does not fall any faster either.
*edit
I forgot grabs!
With the two play styles I said earlier, each uses a different grab of choice. A Aerial mario will use D-throw mostly, and Up-throw. A campy or grounded Mario will use f-trhow mostly.
As for stages, Lylat is neutral with a Lucario Vs Mario match. The stage isnt flat. We all know at the "wings", bend down a light degree. This degree will stop a AS, it will Not stop a fireball. Also the ledges, allows a Mario player to drop from one and get a D-air from it, possibly becoming a threat. And the ledges can save/kill mario. More space to land on, but because they are low, a lucario Up-tilt or Upsmash will go through. Also its a small stage, so theres less air room. Again hindering and helping mario. More room for saving himself, but that also means the walls are closer. So a nicely unexpected AS can kill or even a second Fair.
And gimps for both sides, but Lucario has a bit of advantage. The wings have caused many headaches for many people, with many characters. Get underneath the wing, and you cannot save your self if your out of jumps and/or your Up-B doesn't curve. Lucario doesn't have the wing problem as bad as some characters (i.e. the space animals). Just curve around and on top of the wing, or just go to the other one. Mario will hit his head and fall.
-t2