Actually, my connection is good. I don't get lag when I play Hero, Jack, Joe, Foo, ect. But when David joins then things get iffy. I've had lag with Suko in the past.
When I played him that first time tonight we had a little lag but not this bad. Now that I just played him again 1v1 it's even worse. Ugh!
I'm pretty sure lag is mostly due to a players connection and not so much due to Nintendo's server. Otherwise I would have lag occasionally when I play, and I don't. Not until a known lagger joins the mix.