Oh I know, which is why I want to elaborate now.
First, I question the validity of any Super Smash Bros tournament or game-playing that actually bans certain Smash levels from play. I understand that certain characters on certain levels may have some inherent disadvantages, but in my rather extensive experience, the disadvantages are negligible.
From what I can see, Planet Zebes, Mushroom Kingdom, Pikatown(real name???), Sector Z and Yoshi's Island are either banned outright or not played based on character choices.
That's five banned levels out of nine. More banned levels than played... In my opinion the purpose of a tournament would be to find the best Smash player, and the best Smash player should necessarily be at least competitive on all levels. Especially in Smash 64 where the levels and characters are pretty balanced. Sure, taking away Planet Zebes or Sector Z or Yoshi's Island would lower Samus' stock, and raise Pika's, but then again, disallowing Pika from using his DownB would do the same to Pika. We don't do that because the move is in the game and therefore should be featured. The maps are in the game and so should be featured. It seems to me that if you feel Ness has a disadvantage on Pikatown(real name?) than maybe you shouldn't pick Ness. Or maybe just deal with it, I do, and I rarely take 4th on Pikatown (my favorite level besides Hyrule)
That being said, even taking the levels into account, I still don't think any character could be said to outweigh another character (except maybe Jiggly). Now, if one said that this tier was based entirely on 1 v 1 matchups (I couldn't figure out if it is or not) I would again, question the validity of that. Smash Brothers, in the end, is a 4 player brawl. 1 v 1 is for when you've eliminated the other two players. Any advantage one has in a 1v1 match may be entirely erased in a brawl. Pikachu vs Samus on Dreamland can sometimes be a little ridiculous for Samus. Put two other characters in the mix and suddenly a lot of that advantage goes away.
Now, addressing the actual characters. Pikachu has certain advantages, his(her?) arial attacks are sometimes ridiculous, his upB makes it very hard to rule the edge sometimes, etc.
But Samus has other advantages. Her slow fall and downB (a most unappreciated move) make her, in my humble opinion, the undisputed Queen of the Arial Attack. Also, on larger levels, ironically banned from tournament play, she can be very difficult to kill, especially on Sector Z or Yoshi's Island. Dreamland isn't her best stage as the platforms can take away some of her best arial combos, but it's all about changing your style of play based on the level. Her grab and quick slam (quickest slam in the game I think) rise in stock, and strangely enough, her downB can do some serious damage. Also, on Dreamland I feel her regular B attack rises in importance, normally used as a distraction or a setup in my style of play, it becomes more of a legit weapon on Dreamland due to size.
On Jiggly, that's kind of a point of contention in my little group of Smashers. Her(his?) Bmoves are underpowered, especially in a brawl, and while very lightweight and easy to knock off the platform, she doesn't have much beating power.
Contrast that with Link. His Bmoves can make a VERY strong argument to being the best in the game. Both the Boomerang and the Bombs are excellent for setting up combos and are decently hard to block, his A moves are all powered and easy to hit, and his upB is perfect for being surrounded. He is easy to knock off and once off may be done, but I think his strength and balance more than make up for that. Link is the most balanced character in the game, with the possible exception of Mario. But Jiggly is higher than Link on this list. I can't even begin to see why.
Maybe I am missing something, but I've put in over 10,000 hours of smashing with some very skilled, very equal opponents. The smallest advantages and disadvantages usually show up with glaring repercussions. I've yet to notice any character that dominates more than any other, unless of course we're talking about Link, who seems to dominate on my 64 about ten times as much as any other character.
Also, any stats based on anything but game-time on a 64 console is inherently flawed. I don't know if emulators are taken into account, but they certainly shouldn't be.