Tips:
1. YOU CAN DESTROY MISSILES WITH AERIALS. If the Samus is spamming missiles at you, nairing or fairing through them is really good, since those moves have lingering hitboxes. Bair works to, though the timing is tighter. Best of all, the missile doesn't cancel the aerial, so that you can hit the missile and Samus in the same move. This is great if the Samus is being lazy and not SH auto-canceling; just watch out for crouch cancel. You will need to be smarter with a fully charged charge shot, however, since that's too strong to clink with a jiggs aerial. When she has the charge, don't be afraid to airdodge, and try to avoid landing lag. Charge shot is really a problem for jiggs, so you need to keep the pressure on to avoid letting her get too many of them.
2. Go ham on Samus' recovery. If you just let her bomb jump back to stage, she'll be really well off between the combination of grapple and screw attack. Instead, go out for her when she's near the blast zone. You have plenty of jumps; use them! If she tries to missile you, you can fair through it, as before.
3. Space your bairs, and avoid landing near her at all costs. This is probably one of the best ways to beat wavedash back --> CC dsmash. Samus is a very tall character. Hit her in the face, not the legs, high enough so that you can midair jump again without being in the vertical range of dsmash for very long. If you do this effectively, she'll probably switch to wavedash back --> ftilt, and you'll have to switch things up.
4. Nairs and fairs, and even badly spaced bairs, on a defensive Samus at low percent are a bad idea, since they're easily CC-able.
5. Cornering samus is a very good idea, since it takes away her very strong wavedash back option. Her roll is terrible, so be ready to punish if she tries to roll back to center stage.
6. A shielding samus is looking to wavedash oos, nair oos, or screw attack. Due to her height she is vulnerable to shield stabs, so aim for her head or her feet with bairs, though the head is better since it avoids you having to land next to her with landing lag.
7. Rest: You can punish badly spaced dsmashes and dash attacks with rest oos. This takes some practice. You can also cc the dash attack at low percents into rest, like with most characters. The landing lag of screw attack can also be punished with rest, though you need to avoid the hits. You can try uptilt-->rest at low percents, but be aware that samus is too floaty for this to work for too long.