Heres a little detail about the Fox vs Peach MU.
The key to the MU is to get the lead.
Simple, If a peach ever manages to get a lead on a fox, this could mean fox losing the match. Fox will have to approach, his approaches arent that good to be honest, and the slightest mistake can get him combo'd for an easy 50% more on our favor. The idea is to campwith your turnips, it will be difficult for the fox to enter. If he starts camping, this is not a problem, just camp the same way with turnips, shielding the lasers you can.
Once you go on high %, dont worry about this, fox can easily kill us as soon as we get 95%+, this is were you must be Careful!! You must not approach fox as frequent, using and relying more on turnips!
SHIELD!! SHIIIELD!! shield is probably the most important part of this MU, fox can kill very early, but a predictable Usmash or attack is easy to block, Fox holds many predictable attacks, If ever under pressure, DONT ROLL, DONT DODGE! he will surely get an Usmash, i find Fox's kill moves very predictable, making it hard for him to get the kill, I try not to approach ever, using turnip game, and if he ever gets close, USE YOUR SHIELD, the most he can do is deal more damage with a GRAB, but it wont hurt, since it wont KO us, ive gotten to live up to 180% and almost 200% just cause fox couldnt land a KO move.
Dont fall into Dair games! you can easily shield EVERYTHING. Avoid Shine mindgames above you, if a fox is approaching, fall back, and wait.
We can also punish his fails to Kill, raking him more %.
Also fox is very gimpable, i you manage to get a chance to throw him of the stage, please do!