I do not want to spend my 2000th post talking about CoD.
NAIR
Non-fastfall nair and delayed non-fastfall nair are both pretty awesome. The weakness of fast fall nair when spacing is that certain sections have less range and act as a weakspot for a short amount of time, and the part that we want out may not last as long as we want. The longest part of fast-fall nair that we want to hit usually happens when we are still quite a ways above the ground (a tiny bit after we initially fastfall).
non-fastfall nair helps hit opponents where we can't predict where their next immediate position and allows us to move in an area of more general safety. Hitboxes also last longer, and goes underneath and behind us, which is really nice. If we hit someone with the back side, that's combo potential depending on how they DI'd.
If we delay using nair and don't fastfall, we can have a decently long hitbox that covers us even when we land. It gives us more time to respond to other attacks because we did not commit to nair yet. It also gives us similar followup potential to backside nair.
There are definitely times where ff nair, non-fastfall nair, and a delayed nair would be most useful. Experimenting with non-fastfall and fastfall movements will help with timing in being able to iron out blindspots/weakpoints.
TRACTION/Uses of Ike's Internal Characteristics
From the brawl tactical discussion forum, I learned that Ike has one of the top traction levels in the game, which means he's quite slippery. This means that using normal shield is not as effective. Unlike Luigi, though, our traction isn't to the point where it's horrible. It's actually quite good.
1. It's harder to get caught in a platform techchase
I have used quite a few characters, and getting caught in a platform techchase is NOT fun. Most of the time, when I use Ike, if I DI up when hitting a platform, I usually slide off, or simply jump out.
2. Dashing/shield dash
As many of us already naturally do, Ike players tend to dash a lot, even though other characters have turned to walking. Why? Ike sports a very nice initial dash speed for a "slow" character, having an initial dash as fast as Marth and Sonic. This, coupled with Ike's very good close-up game is a godsend. Simply dashing away becomes a viable option most of the time, because the time difference is large enough to respond with something like shield, jab, bair, whatever.
If you mix Ike's low traction with his pretty decent dash speed, one can slide with his dash a pretty fair distance. One could jab Lucario's mid-high percent fsmash that way. Mix this with advanced control like shield DI, jab and bair punishes go from alright to legit.
3. Up-close combat + SDI/More on traction
Ike is capable of winning close quarters combat on just about every character bar MK and grab-centric characters (which are more punish-based). Against characters with jab like snake, sonic, etc, simple DI allows us to slide away and punish with our own farther-reaching jab.
Every jab is SDIable. Ike's and falco's (single jab) are probably the only few that have options against SDIing jab (maybe Luigi, too? Don't care enough). Against falco, we can still DI the single jab and interrupt the grab attempt or attack, yet he can shield, so making sure jab1 hits at its farthest distance guarantees the most safety.
If someone SDI's Ike's jab, we can still jab1 most of the cast if they didn't pop out far enough to even take away their double jump, which is when the pain truly begins if you can successfully predict when they do/don't try to attack, and their escape/DI method as you mix jab1s and jab2s with a little bit of combat walking. If they use their second jump to escape, we have multiple aerials that outrange most characters (most can't double jump again to space) as well as a far reaching dash attack and decent initial dash speed. We also have situational utilts, bairs, grabs, etc that we can use at will.
Just like Mr. Doom, you can SDI other people's attacks and follow up with your superior up-close game (or just get the heck out if you feel like it), probably dishing out just as much damage as they gave you anyways. An example would be SDing a jab away, then jab interrupting their followup, or SDIing behind snake's ftilt or something. QCDI by rotating the control stick is the most effective way to SDI without thinking or preparation time.
Moveset situations
Ike's entire moveset has more uses than we think (bair, tilts, etc)
Ike has many traditional ways of killing, but he has like 1000 read-based killers that aren't even all that unsafe most of the time. Just requires timing and situations must be right to minimize whiff-punishment. Utilizing more of Ike's moveset in general makes it so that we see less fair staling and things like that.
Jab2 is very underused in its own right. It is a very quick option after jab1 to interrupt low-level aerial approaches. It's difficult to grab if the kick hits shield at max distance. We only commit to using jab2 after jab1 if we purposefully decide to do it. Can't tell you how man times I interrupted someone else's move with smart use of jab2. After you get a jab on someone, it shouldn't be autopilot. You must actively observe escape options, attack options that can stop the jab cancels, and have correct knowledge and move understanding in order to act accordingly. Looking at DI and if they used their double jump or not and your surroundings on stage are also important. Jab3 can be used to interrupt, too, although more situational and can be reacted to.
Bair is a very usable move. It's biggest weaknesses consists of small characters, characters who can punish our landing to the ground (so fullhop bair->double jump may be a possible mixup) and the global issue that we need timing to land it, we can't just use it in every situation. Funny thing is is that bair is probably one of our moves we can spam the most, though. RAR bair can definitely be used when reading an aerial approach. I also experienced myself that bair offstage isn't that much less effective than fair offstage (more telegraphed though), and bair is very effective vs characters like Marth and MK when they're in the air. We should be spamming this move more often, especially if we retreat it (especially retreating the RARs).
Keep in mind that we can use bair, fair, non-ff dair, and uair at ledge level and recover with a double jump easily. We have more than enough time to mix up aerials offstage.
Ftilt's biggest weakness is whiffing, of course, but is most effective used near the edge. Angled down ftilt hits most characters hanging from the edge, and is our "projectile" to force opponents hanging on the edge off. If an opponent shields ftilt at the edge, it pushes them to the edge again unless they're super heavy. I believe there is shield poking potential if we fiddle with which directions to angle ftilt.
Eruption is like the easiest air dodge punisher that we have. It gives us sufficient time to charge it up a little bit while they air dodge. It's good vs horrible MKs , too. I find it effective to use eruption in the air, after a fullhop, when the opponent is trying to get back to the stage, against characters with only 1 double jump. I don't use it very often, but the times I do in the situations described above works wonders.
For dair, the quickest thing I can think of for those attack-stick users to avoid getting juggled, use non-fastfall dair. But it's not over yet. You must move away from the opponent while doing this. Opponents can easily try to attack you after the hitbox shrinks after the initial spike hitbox. Ike's aerial speed is pretty decent, not bad enough to have that much of a speed disadvantage when holding one direction. I can't think of too many times dair would work best other than hoping they jump into it. I use it vs MK, just dair above and fall away. Mixing up fastfalls and non-fastfalls also help.
Fair I talk about too much already. Blindspot when landing (especially on fullhop) good to use offstage, etc.
Uair we already use a lot. Some of us like to use it on grounded opponents, too. On snake, I think it shieldpokes if uair hits the top of snake's shield really easily. I don't know, the roflcopter's just useful in many ways. Back side of Uair has better horizontal distance, while the front side has a part of the hitbox that hits more above Ike. It's super **** to uair an opponent that as to recover to the stage after we grab the edge (Marth the most extreme example)
Utilt is a move that we just have to learn to find the right timings for. It beats most attacks, but loses to most airdodges and we don't like to miss. I can't think of many times to throw it out without a setup, because our other moves really cover all that.