ZSS: *Shrugs*
Samus: Spam projectiles. After all, her arm is a stinking gun. People may gripe or complain, but that's because they'd rather spend their time complaining about their loss then actually searching for a way to beat it. (It happens in EVERY game, people are just like that. That's one reason why I'm not competitive anymore.) For more detail about skilled spamming, see also:
Brick Walls & Traps - by Emblem Lord
Always keep your Beam charged as muchas possible. That should almost always be the first thing you do at the start of every match. Once you have your beam charged, don't shoot it right away. People will almost always expect you to shoot it right away, so they'll make unnecessary evasive manuevers. Take this opportunity to punish them for it. Try to save your charged beam for an unexpected moment. Remember, the closer you are when you fire it, the less time it takes to hit your opponent. Just be cautious about reflectors.
Avoiding Reflectors: If you're playing a character that has a reflector of some sort, and think they're smart for over using it, it's possible to irritate them out of using their reflectors via Homing Missiles and Zair, providing you more of an opportunity to land a charged beam. For example: Fox. Just fire a couple homing missiles, and MAYBE a Super Missile or two to bait out their reflector. Keep a distance when firing the SMs (Super Missiles) so you can safely defend. Once you've baited them to begin using their reflector, Zair does the absolute trick. Performing Zair even confuses your opponent that you might be Missile Cancelling again or something of the sort, so Zair will constantly come as a surprise. You might even be able to follow one up with a Charged Beam.
Which reminds me, know the timing for Missile Cancelling well. Learn how to shoot between Homing and Super Missiles at will. Variety is important. I wouldn't shoot a missile unless it's cancelled, or if I'm just completely sniping from huge range.
Try to stay at distant combat as much as possible. Samus doesn't do too swell at close range.
Things to do out of Charging a Beam aside from just shielding and rolling:
-UpBOoSC (Up B Out of Charged Shot)
---While charging, quickly shield then perform UpB (Screw Attack). Tap Jump must be ON for this to work. The shield should be so swift, you shouldn't even see it come up at all. (Very usefull against opponents who approach from the air while you're charging.)
-BOoCS (Bomb Out of Charged Shot)
---Quickly shield to cancel charging the beam like before, and press Up to jump out of the "shield" (even though you should be doing this so fast, the shield shouldn't even come up). Once you've jumped out of the shield, then quickly press Bv (Morph Ball Bomb). If done quickly in sequence, you shouldn't even see Samus shield or jump, just lays a bomb right from charging her beam. (The shield cancels the charge, and the jump cancels the shield, allowing for freedom of any aerial movement.)
NOTE: I usually try to do this while on the ledge. Once the bomb is deployed, I DI backwards off the ledge. The opponent will usually ignore the bomb and approach in attempt to intercept you. DJ back towards the stage, and your bomb should combo with either Fair, Uair, Nair, or Dair (preferably Fair). Combined with the Bomb, Fair has the ability to pierce through the enemies' shield with the last few flames that come out of her gun.
-Aerial Dodge OoCS
---While charging the beam, hold Y (the jump button), and press L (the shield button). Instant aerial dodge right off the ground, a good evasive technique. You can even Zair out of it, too.
MC to Grab. Cancel a Homing Missile, and follow up quickly with a grab. If the enemy blocks the missile, they have no choice but to get grabbed.
Hm... There's more, but that's all I can think of at the moment.
EDIT: Here's the most recent video of my Ike. I was playing with these With Anyone guys who thought it would be fun to start a Taunt Party. When I broke the party, they teamed against me, and this was the result:
http://www.youtube.com/watch?v=EYqDlJpTm1U
Though I was rusty during this time. You can see I made some easy mistakes.
[/lie