Well, I didn't see the match, so I'm not sure what exactly happened.
I can say this much, though. Zelda goes just about even with Ice Climbers if I remember correctly (and I think I do). She can absolutely wreck the CPU Ice Climber with her aerials, and this is the one time in which Zelda wins in a air-to-air situation. She's also extremely deadly up close AND far away to them.
As such, a well-played Zelda has roughly a 45-55% chance of winning against an equally well-played Ice Climbers. Considering that the matches game down to a single stock, Iwould say that the coin just landed on heads three times for your setup, which isn't a terrible thing.
And sometimes a person can just have your number. Brawl IS a guessing game a lot of the time. Sometimes even tournament-level matches devolve into a complicated game of rock, paper, scissors. If he was just in a zone and called what you were going to do every time, it's quite possible for him to reverse it exactly as you do it (hence the "psychic shoryuken" effect), especially online.
I'm not telling you anything you don't already know. You don't suck at this game. Neither does your opponent. If you lost, take something away from it. It would be boring to win every match you're in.
Whatever you do, don't drop out! I still want to face one of you in the finals!
(Edit: Also, don't make the extremely common mistake of assuming that an opponent won't learn from his mistakes! If you 3-stocked him previously, chances are good that he'll realize what you were doing in order to do that and be looking for that.)