Imo , the cf matchup against every character is is simply to get cf off stage and edge guard. I think peach has great tools to do this against cf effectively, ie turnip spamming and great knockback on all her nair, fair and bair. A simple tech chase, foward throw near the edge against cf is very effective because of f throws knockback, trajectory and peachs edge guard options (god help you if you miss a sweet spot) Also cf kills are mainly horizontal kills and peach's recovery is very good against that. Even when l canceled, cf does have a good sized lag and peachs buffered dash is very quick for an easy punish.
a lot of roys like to cc d tilt to start combos, peach is very good against players like that with downsmash. I think roys recovery is very bad and peach can easily get him off the ledge and from there effective ledge guarding should put roy away. And good di against a roys down throw and/or a fair at early percents will make roy eat a nair that comes out very quickly. Peachs recovery is good against roys kill moves. And roy needs to get up kind of close to kill peach and peach can hold her own in the short game.
As for link, i will take your word for it, but the reason why i said she does well against link is because her float stall can bait out links attack moves such as links dash attack, fsmash, and up b are all very laggy. She can float above range of links arrows and bombs. Also, her dash attack clanks with most of links projectiles. Also links up b recovery trajectory can be traced pretty easily and can be setup for a punish. Also float cancel into quick aerials is effective against link due to some startup lag against links fair. when peach is down thrown at early percents she can just nair very easily to prevent a combo
I agree with you link is somewhat of a tough mu for peach. I think in larger stages (fd and smashville for example) give link a clear advantage. Also its very easy to eat a down air when chasing link in the air because peaches hops arent that high. But on smaller stages peach wins because links startup lag on his projectiles arent quick enough vrs peaches dash attack