Why is X a counter to Y?

[snuffysam]

I'd like to learn a little more about the Smash metagame and what makes certain characters good. So I looked up counters to see which characters are good against what other characters. I figured, for example, that characters like Jigglypuff would be good against characters like Bowser, since Jigglypuff's good attacks work well against big targets who can't jump too high. Stuff like that. But instead I find these:

http://supersmashbros.wikia.com/wiki/Character_matchup_(SSBM)
http://www.ssbwiki.com/Counter_(matchup)

While these tell me a lot of information, they barely explain anything. Like, why is Peach apparently so good against Ice Climbers? Why is Fox moderately good against Shiek? Stuff like that.

Anyone who plays a particular character care to explain their matchups?

 

[Narpas_sword]

Character Specific Forums tend to have a matchup thread you can look at.

 

[Stride]

Those matchup charts are outdated and were not particularly widely agreed upon anyway. Also, you should just ignore the wikia; SmashWiki is better in practically every way.

For Luigi: his bad matchups are mainly those that are able to shut down his ground movement, take advantage of his short range, or abuse his poor recovery and floatiness. This means his bad matchups are virtually the entire top tier, but most overtly Sheik and Spacies.

You'll be able to work out why matchups are what they are just from experience, as well as listening to commentary and things. And what Narpas_sword said, of course.