All I can really say about Peach in tournament play is(in my opinion) it is VERY UNLIKELY that a peach will win a "national" tournament. The tiers in melee just play too much of a factor(again this is my own opinion) in melee. Sure I win some local tournies with Peach and what not but when I travel out-of-state it becomes much harder and usually it means I'll have to switch to Marth or Fox to handle some matches because, unfortunately, Peach just doesn't have what it takes to handle them. I like to play Peach, but when I'm playing to WIN, using just Peach is imo just too much work.
For example, when I played Forward's Sheik recently with Peach. I kept getting 2 or 1 stocked, over and over and over. I couldn't win. I'd probably win 1 out of every 5 matches we played. Did I change characters? No, but I think I could have done a bit better on the win ratio if would have chosen someone better.
I won a national tournament last year at Midnight Gaming Championships in Dallas, I stuck with Peach the entire time. Do I think I deserved that win? I don't know, there were so many good players there, I was lucky enough to avoid some of those players in my bracket. There were a few close calls and some matches where I still think I should have lost. Sure there was some skill involved, but I think I just got a lucky break. I think Wobbles should have beat me and took the tourny but I was lucky enough to take the win.
So in closing, do I think that I could ever do the same thing again at a national tourny with Peach? Most likely not. You just have to ask yourself is it worth the effort you have to put in(and a lot of luck involved) to try and win a tourny with Peach.
Sorry this post is so sloppy, I'm at work and I'm on my 15 minute break so I had to make this quick >.> I'll make it sound more professional and awesome when I get home
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