I dunno who you play, but some characters do hilariously predictable things. For example, a level 9 MK knocked off the stage will almost always go for the ledge. Thanks to good timing, I killed one as Ike three times in a row with down tilt (it's a meteor smash) after throwing him offstage.
Basically, go test things, and try all kinds of stuff - if you get creative, you can find holes in AI, even advanced ones (the Project M AI, while "upgraded", has some especially hilarious problems).
As to the second half, Ike has incredibly powerful attacks, but he's not the best character - I'd say in terms of raw damage output, Snake has the lead, but in terms of damage per second, you're either looking at Ice Climbers or MK, since ICs can infinite people and quickly raise damage percents to well over 100% in less than 20 seconds, and Meta Knight is the character most conducive to stringing attacks at lower percents (for example, utilt -> utilt -> SH uair -> uair -> uair -> ... -> uair -> nair or Mach Tornado or even Shuttle Loop).
All that said, newer/inexperienced players tend to not use many defensive options at appropriate times, so Ike's smash attacks can seem difficult to avoid, and they are some of the earliest KOing smash attacks in the game (while he's not the strongest in any category, his usmash has a wide area and his fsmash is top 3). Since all his normal attacks (tilts [except dtilt], aerials, smashes, and jab) can KO around 150% when fresh (jab needs to be on the ledge), he can seem very strong at first glance. But as I stated above, when people improve at spacing, dodging, and reading Ike, he begins to seem as many view him now - having a few good attacks, but mainly being very laggy for his most powerful moves and rather gimpable, so he must be played very patiently and attempt to KO either with a hard read or with one of a few tricks that are basically all escapable.
