Well, I can't say that it's going to really help me out. His Sheik whooped me last time! He doesn't even use Sheik. :/ But I won with Peach.
We like to have our occasional Falcon Chronicles and Ganon Battles for fun. XD I think the Falcon Chronicles helped my brother, though. He beat my friend's Link with Falcon tonight and then told him, "Show me your moves," when he won. I'd say you should look for good players. Maybe at school or something.
I do believe wifi helps for practice, but I wouldn't become too reliant on it. What Ref said probably does hold true. Of course he goes to tournaments, so that could be his way of getting better with Ness. I have to thank Earthbound360 for training my Ness months ago. Right now I've been playing Shaky and
Chrono_Cross which have good Ness' and I do believe they've helped me learn something.