Not necessarily. A cliché is anything "which has been overused to the point of losing its original meaning ... rendering it a stereotype." Many unoriginal ideas can become original simply by the approach an author takes.
From what I know of him, I would not consider Karasuma a Mary Sue character. For example, how does his role affect the protagonist's development? Surely the protagonist faces difficulties against Karasuma and grows as a result. The author also poses a legitimate answer as to why Karasuma is his favorite; he was not designed to be "flawless and talented" just for the fun of it, but to act as a foil for the protagonist / other characters.
Whoops! I guess I got stereotypes and cliches mixed up.
Well that was the intention, regardless: to bring out the reactions from other characters. Think about it. The moment we begin watching School Rumble we sit and gawk at the surprisingly (or unsurprisingly; depends how you see it) unrealistic feats of this guy which puts the protagonists through interesting phases, which again in turn brings out comedy. XD That's what I'm talking about.
On a different topic,
1) I'm tasting blood. F#&$!! I may have recovered from my illness, but my cough is worse than ever.
2) Sometimes I skip classes when I don't wanna go, but other times I skip classes when I
really need to go. Was ready and such though a bit late, double checked everything, my stuff and my bicycle, began riding halfway through the four miles journey and my tire busted. -.-"
3) I must admit that, though I'm neither a Justin Bieber fan nor am I a hardcore hater (I actually respect the guy), some creative discrimination is awesome to read since it's really,
really funny, such as at Cracked or some witty jokes. It's also sometimes healthy community-wise. But now it's not only getting out of hand, but also getting really annoying really fast, just like the Twilight effect. Why, you say? Just received a Graphicsly Newsletter (seriously, where's the
professionalism in profession?).
Check the attachment.