Hmm ... well I never came across a cheater in Mario Kart. However I think online cheating will make a bit worse, not completely ruin it. I mean, how many people own an R4.
In animal crossing. I hate those people who ruin other peoples' towns on purpose. I don't mind getting helped by nice hackers who give you stuff.
I really hope Nintendo does something about using cheats on Wifi. I wonder if they'll have securities monitoring the matches? Like if they catch you cheating then they can kick you off with a wifi loss record. That or blacklist your DS so you can't use wifi for that game anymore (Or at all).
In animal crossing. I hate those people who ruin other peoples' towns on purpose. I don't mind getting helped by nice hackers who give you stuff.