I've actually been thinking about Peach and Dreamland for a few months, now.
If you look at the way Peach plays
most of the time (not all), it's a fairly linear set of strategies. Float-canceled neutral airs and forward airs, roll to downsmash, dash attacks, maybe down air to downsmash combos, with a healthy dose of turnips and jabs mixed in. What I'm getting at is the fact that her knockout moves on Yoshi (dash attack, neutral air, forward air) are all a pretty consistent part of her on-stage strategy, too. That being said, her main on-stage tactics lose their power, thanks to damage reduction (although I don't think any significant testing has been done on whether knockback is reduced or not, but we can
generally assume it is), quite rapidly. This is significant because Yoshi is so heavy--if we make a general assumption on at least minimal knockback reduction correlating with damage reduction, then Yoshi becomes increasingly harder to knock out as a stock goes on, especially on a big stage such as Dreamland 64. Toss in some skill/luck DI, and that's pretty powerful.
I've lived to 320% on Dreamland 64 via DI (either by luck or skill) by aiming for the very top corners, even against very horizontal moves.
While I love tooting my own horn, this is more to get the point across that if you approach KOing Peach
a certain way, then you can see some marginal success in survivability and perhaps in overall match outcomes. My number one way to KO Peach on any stage with Yoshi, regardless of size, is a meteor. She simply does not survive for even an acceptable amount of the time for her. No matter what stage, you can almost always count on a KO in the
downwards direction. In truth, the best part of this tactic is that even if you miss, they cannot retaliate until they grab the ledge (unlike Sheik, Ganondorf, Marth, etc.). On some smaller stages, I'll go for horizontal KOs (Yoshi's Story, Battlefield, etc.) even though she's heavy, but I do that because it's much easier to knock her away and risk her coming back than trying to get under her and almost never get a chance to KO. My secondary tactic to meteors is being quite homosexual with down tilt. If you thought down tilt to down tilt to edgehog works on tournament Falcos (and it does, just for the record), wait till you see it on tourney Peaches. It has about a 60% rate of success, and most other times you can angle a forward tilt or toss an egg or something if you see it won't stop them from grabbing the ledge.
One of Sheik and Fox's main ways to gay Peach is just to stop her from ledge grabbing.
I submit to you guys that if you take an approach similar to this in your KO philosophy on Peach, you may see some sort of turnaround on Dreamland 64. **** taking Jigglypuff there, though. >_>