I wouldnt expect it to work on good players but that samus is very predictable, what I would do is when he jumps above you wavedash back right before he starts his attack and wavedash back in for either a smash or a grab, also you can nair through missles instead of trying to jab them its a little safer, I still preffer jumping, double jumping, wavelanding and patience to deal with my missles but if you intent on destroying them with a hammer nair is a better bet and can also lead into a free hit. If your friend crouch cancles the nair though be prepared for some horrible things to happen to you, which is why I would only use it on noobs. When he goes below the stage you can interupt him with ice blocks or you can nana charge a fsmash and then edgehog with popo.