In the mirror PP, how do you mitigate the fears of getting reversal on? Although not a big chance for me, there's a sizable chance where I just get fsmashed/faired/grabbed/DA'd whatever from corner from ledgedash, DJ attack (like fair) from ledge, WL down fsmash, DA/Fsmash from corner, SH/FH from corner to beat my dtilt, spotdodged, and whatever abomination cheese strategy the other Marth has. Thing is on my end, these tools fairly often works as well and sometimes netting a stock, so I'm not really seeing the true benefits of holding center as opposed to being cornered.
Why do you think spotdodge is bad in the mirror? I often see whenever a Marth tries to grab the opposing Marth but the opposing Marth spotdodges, the opposing Marth often has the slight advantage with crossup grab or something. Additionally because Marth's spotdodge lasts awhile, it has a niche use in the mirror where it can just beat some moves straight-up with a clear opening for the Marth that spotdodged. Obviously it can be read and punished, but that goes for going for any other defensive options like dtilt as well. Currently I'm not really seeing as to why spotdodge is supposedly terrible when I think it has great niche uses atm.
What's your general flowchart of covering low up-b's when the Marth is reactively avoiding challenging your bair or something as you go out there? I can't really explain it super well atm, but imagine a scenario where you launch the opposing Marth where he can't quite recover high as an option, and as a result his mixups are to DJ to ledge or to recover low (as well as the mixup of DJ/side-b stall if I hog ledge). Right now I'm struggling to find answers to reliably beat low recoveries without having to resort to really risky attempts (which I consider the M2K going down to up-b pretty risky) or reactively fsmash coverage vs low up-b, but this loses to wall tech bair where I get hit for my own edgeguard. Do you have any suggestions?