The Master of Mario
Smash Journeyman
I don't think sliding D-tilt is a good approach option because D-tilt takes as longer than Mario's Frame 5 tilts to attack (taking 12 Frames). This leaves peach open to faster ground attacks like Mario's F-tilt or D-smash hitting peach before the move comes out. Peach's F-tilt and U-tilt in a similar respect both last longer than Mario's D-tilt so it leaves Peach Vulnerable to OOS attacks. Peach may be as fast as Mario on the ground with some moves but overall her ground game is slower and laggier. Any use of Peach's ground game will be telegraphed leaving her open to approach options after shield/dodges.
Mario's Fireballs are good because of the amount of Frames the fireball lasts after the attack has come out. With Good spacing this can easily lead to approaches with other attacks like F-tilt, grabs, OOS attacks or B-air depending on how the opponent reacts. When facing Peach fireballs slow down her airgame because in the air she loses the ability to shield and her options for dealing with fireballs all have lots of lag.
I don't think Peach will have an easy time approaching this match. Mario will also have a much easier time KOing. The only thing that keeps it from being in Mario's advantage is damage racking & combos which peach will have an easier time if she gets the right hits to land. Mario has to focus on punishing peach's laggy moves with damaging attacks F-smash and/or D-smash, U-air OOS, B-air OOS, Up-Special OOS, Shield Grabs, Blind-Up-smash OOS. Mario has to also control spacing with faster but less damaging hits N-air OOS/F-tilt/Jabs and pressure with fireballs/Fludd to stop her airgame so she retreats to the edge of the stage where Mario's Up-angled-F-smash/Charged-D-smash will KO her early.
I think the Matchup is around 50:50
Mario's Fireballs are good because of the amount of Frames the fireball lasts after the attack has come out. With Good spacing this can easily lead to approaches with other attacks like F-tilt, grabs, OOS attacks or B-air depending on how the opponent reacts. When facing Peach fireballs slow down her airgame because in the air she loses the ability to shield and her options for dealing with fireballs all have lots of lag.
I don't think Peach will have an easy time approaching this match. Mario will also have a much easier time KOing. The only thing that keeps it from being in Mario's advantage is damage racking & combos which peach will have an easier time if she gets the right hits to land. Mario has to focus on punishing peach's laggy moves with damaging attacks F-smash and/or D-smash, U-air OOS, B-air OOS, Up-Special OOS, Shield Grabs, Blind-Up-smash OOS. Mario has to also control spacing with faster but less damaging hits N-air OOS/F-tilt/Jabs and pressure with fireballs/Fludd to stop her airgame so she retreats to the edge of the stage where Mario's Up-angled-F-smash/Charged-D-smash will KO her early.
I think the Matchup is around 50:50