There have been 4 generations of smash thus far, and all of them have had very different play styles. Because of this, if you get good at one version, you probably won't be good at any of the others. In Melee, many advanced techniques (Abbreviated as "Techs") were introduced, including wave-dashing, unlimited ledge invincibility, and hard aerial combos. Brawl removed these techs, and introduced features like the dreaded tripping and multiple air dodges. The latest iterations of smash created ledge-trumping and grab limitations. But these aren't the only changes. The games all fundamentally play differently. Melee is very fast paced and its hard to escape combos once their started, due to the limited air dodging. Brawls removal of advanced techs and the introductions it made caused many to consider it a "casual" form of smash, and it has since been almost completely removed from competitive smash being replaced by Project M. Smash 4 has found somewhat of a balance between these. Many people play casually, but it also has a huge competitive scene. It is also the easiest game to get competitive at, in my opinion.
Tier lists are seen by people as either brilliant or garbage. However, there is no denying that they're here, and constantly changing. For the uninitiated, a tier list orders the characters in smash in a best-to-worst format, showing you the best characters, and worst. Some say they don't measure anything, and that they have no logic behind them, but based n what I see, they definitely mean something. I haven't seen any tier lists for smash 64, but in melee the top characters were Fox, Falco, Captain Falcon, Peach, Jigglypuff, and Marth. You might expect the tiers to remain somewhat the same, but you'd be wrong. Marth and falco stayed on top, but all the others dropped, some significantly. Peach and Fox fell into the middle, and Captain Falcon and Jigglypuff fell to be some of the worst characters in the game! The new best character (By a landslide) was newcomer Meta Knight. In smash 4, the characters are far more balanced, so even if some characters are considered "The worst", they're still pretty good. However, a distinct top tier emerged who were undeniably more powerful than the rest, and that character was Diddy Kong. He had an incredibly powerful combo, good for racking up damage and killing. Although he was later nerfed, he still has a large competitive presence, being towards the top. However, the new top tiers are Sheik, Rosaluma, and Zero Suit Samus.
With all of this being said, it's clear that smash has changed a lot over its generations, and that's a good thing. With all these changes, it gives us all games we can enjoy. Some love Brawl, others hate it. But either way, we can all find a smash that we can enjoy, and it's because of this that I say as we approach the one year anniversary of smash 4's full release, good job smash. Just keep changing for everybody.
And remember, if you see Kryongor...
Just run.
-GIR