I need to make a video showing all the reasons yoshi and distant planet is broken... for now lets just go with bottom of slope is a perfect camping spot for eggs, usmash, and sh uairs, the walkoff lets us abuse our amazing grab(fthrow cg on a few chars at low %'s, along with the grab release on a small number) , sliding ground pounds on the slope, when its raining you can DI towards the stage, and never fall off the edge. You can even do lagless uairs on it, the water will cancel the ending lag so you can do like 5 per second, the water grabs them then you spam uair as the water brings them towards you, in a state where they can't airdodge or anything. You can land it pretty easy. Though when you do land one, you fall off, it's easy to dj back up.
Back to the long list. If someone is camping that spot on the slope you can ece from the right edge of the main platform and land eggs right there. It's extremely easy to DR up the slope. fthrow->DR dsmash/dtilt owns at low %'s. The pellets give yoshi's djcit some use. You can grab a pellet by nairing the top of the plant, the boot will break the plant and somehow you will pick up the pellet with the same attack. ECE's on the bottom of the slope make it a lot safer than on a flat surface. It's a lot harder to punish being slope down, and if they jump they will land on the platform.
Anyway thats all I can think of for now, but I'm sure there's more... just try it out, its an awesome yoshi stage.