For Mario...
I recommend all Monk said. Especially about the sixth sense thing.
Samus is pretty easy to get with the cape though. Especially the missles, and it's really good when you get her in the face cause she goes flying usually. Whenever I see her stick her arm out I charge and time the cape so the missle returns really close, making it hard to avoid.
If she shields it, grab. If she gets hit then chase her, and get ready to combo or just keep her off the edge. And if you're far away and she's missle spamming, short hop cape toward her, but be ready for a close up attack when you finally get to her.
With the blast, just.. Be very careful. When you're close up or running toward her, the person (well.. The person I play anyway) usually fires thinking it's gonna get you cause you're close, but with enough practice, you can just cape it in her face. (Ask Somebody. He hates it.)
Now then.. Whenever she's recovering.. Don't bother trying to edgehog unless she's under the stage and is about to do her screw attack (which is actually pretty easy to cape anyway or at least I think so), instead fire ball spam, cause it forces her to dodge and recover at the same time. So it can even kill sometimes.
When you're in the air and you don't know what to do, you should usually cape.. I do this usually because you can turn them around, screwing up what they were doing, and leaving them open for a second. With Samus it's usually a good idea to try to cape her b-air.
Umm.. U-airs work wonders.. so do b-airs.. And you could be really annoying by doing a little triple jab to a forward smash.. Or if the damage is too high to do the third jab just do two then f-smash. Usually they can't do anything to get out of this.
I'm gonna give your Mario a 5.8/10. Keep workin' on it. It'll come to you.