lovage would probably be good for advice vs those chars.
vs Samus, you can punish most of her grounded moves, especially if they don't space well (d-smash, f-tilt, f-smash, d-tilt, jab). Some of these are susceptible to WD oos -> shine, or even d-air oos. Don't try to do extended pressure into her shield and space enough so that you don't get hit by that up-b oos. Don't recklessly spam n-air/b-air since she can CC -> punish you for a long time due to her heavy weight. Platforms are good in this matchup as well. If you can try to make them jump after you, then she's a sitting duck in the air. Just keep calm and don't fall for random gimmicks. If they try camping, then use lasers to see if you can make them approach. Don't go crazy though and make sure you don't get hit by missiles while doing this.
Don't be afraid to shield, cuz she can't do much in terms of pressure or getting through it. Still, watch out for grab. Though it's slow, it can still be used.
Waveshine -> u-smash. Then try to see if you can get u-air in or something. Running shine has its uses too. Like try to catch them when they're moving around. It also serves for a great check on her shield.
I recommend grabbing a lot, since most samus will shield a lot. If grab them near the edge, it should be in your best interest to throw them off the level (especially f-throw). If you land a grab on other parts of the stage, KK recommends b-throw cuz if they DI in, you can throw them to a platform, but if they DI away, they may go off the stage which sets up for potential edgeguards.
vs. ICs shine them a lot and target nana always. Then fight Popo like a bad luigi. Platforms are your friend. When you see them WD towards you for an approach, a lot of times it is good to jump to a platform and try to make them jump. Beware of them doing u-air directly below you, cuz you may get knocked down and/or potentially combo'd. If you can make them miss moves in the air as you jump around them with or without the aid of a platform, they are pretty vulnerable even though they have disjointed hitboxes. There are simple ways to space around their moves, and it can get you a big payoff as well. Coming down with b-air is pretty good.
In terms of combos, honesty just spam n-air/u-air when they're in the air and try not to let them touch the ground.
Quick Kills on nana are key, but don't expect it to be super easy if they're good players. One suggestion is to shine them and either one of two things will happen:
- they split up
- they go the same direction
If they split up you should target nana and try to gimp her since she's a CPU.
If they go the same direction, either they may be shined far enough for one of them to be forced to grab the ledge. Since only one of them can hold the ledge, shine spike the one that doesn't get the ledge (usually nana in my experience, but not always). You may have to still do a little more edgeguarding when Popo tries to save Nana.
I also can't stress this enough, but watch out for nana BS while fighting them. It can really be a game-breaking catastrophe if something stupid happens because of nana.
Those are the 2 characters I hate playing vs the most. They're just so boring. I'm not bad at the matchups, but I don't have fun with them at all. Vs samus though, I just go sheik. It makes it go faster cuz of the large reward for grabs.