That is not even close to representing the Diddy/Samus match-up. Honestly. Gimped by Diddy all three times. Samus gimped by Diddy... maybe one time is kind of acceptable... three stocked? O_O
Of course, that was Dec '08. Things change! We know stuff!
Diddy match-up... z-air camp him. The worst possible scenario involves you getting hit by a banana in the air, trading off a z-air hit on Diddy. Much better than tripping on the ground. If so happens you manage to get a hold of a banana, drop it in front of you, leaving your options open and limiting his. And then keep z-airing. (He has to either dash attack to regain control of it, or hit you with a second banana to regain control of the first.) You could glide toss and attempt to combo off the banana, but that's not how Samus plays. Combo off of any free z-air hit you get (chain with dash attack to pick up the banana and reset your spacing with it) or just leave the banana for zone control. Homing missiles work if you're not in z-air range. Otherwise, the extra 1% isn't worth risking a possible trip.
On a side note, do throw any peanuts you catch while z-airing at him.
If the Diddy is honestly throwing the banana in the air instead of glide tossing in this match-up, laugh and keep z-airing. His ground game is too good (the lag on his grabs are ridiculous) so playing the OoS game sucks against Diddy. His aerial game is above average too; significant lag on the f-air, but since he's chaining the f-air off of banana, it's good. Diddy's main problem is approaching characters with higher priority so you kind of have to fight his weakness and hide yours (Samus's subpar close range game.) And like the Falco match-up, gimping is a must.
I'd put it 65:35 Diddy's, but I could see it move towards 60:40 at the least. But if you're playing someone who doesn't main Diddy... or doesn't know the match-up, they will have trouble fighting a Samus, making it seem 50:50. I guarantee it.
.. this should go in the morphology. lol