If I can ask a question out of curiousity, AlphaZealot... I believe the question posed was 'A person who's good at the game with default rules vs. a person who's good at the game with standard tourney rules; who's the better player?' with your answer being the tournament-style player because of the nonexistence (after a certain point) of item tournaments. Does that mean that you would have answered that question differently had item tournaments been the more prevalent format of play?
I view Smash similar to tennis for this example. The best tennis players on clay are still among the best on hard court and vise versa. However, if items play had continued, there would certainly be intricacies that exist unknown to an unexperienced non-items player. Would these intricacies exist to the top non-items players? I can't say for sure, I feel its mostly unlikely because items play, discounting any random occurrences, isn't so deep that it would escape the grasp and understanding of top non-items players, espcially when you consider the similarities between items play and some of the projectile characters in non-items play (Diddy, Peach, D3).
This said, the reality is that non-items play is much more prevalent than items play, with less people playing with items, there exists less competition and a slower development of the meta-game. Considering this is the reality, the best items players will undoubtedly have to also play item less tournaments in order to keep up with "regular" fighting, IE what occurs when no items are spawned.
So: Yes, it could very well be that, had items play developed equally along side non-items play, that the best items players would be different from the best non-items players (and these players would still be near the top in each others arena). The reality though, for Melee, was that items play stopped developing and so far for Brawl items play is developing much slower than non-items play. The result of this is simply that the best non-items players are also the best items players because they will dominate the "regular" fighting in a match, meaning the subtle advantages an experienced items-only player would have would not be enough to outweigh the massive disadvantages of not having the same experience during the "regular" fighting periods as say, Ken, Azen, and KoreanDJ.
Now, I think, from reading the question, your also inquiring about the level of skill, would the best items player technically have more skill than a non-items player? To address that, you would have to determine 1)if items do add depth 2)if the random spawns do not influence matches to a moderate to high degree (even a slight degree could be a problem, as pointed out before, only a single spawn can grossly offset the advantages between two roughly equally skilled players).
Okay, so the general agreement, I think, is that the rules do favor veterans, but it's only because the rules were designed to make an otherwise unbalanced game tournament worthy, and because the veterans have, by definition, more experience playing under these rules.
I'm fine with that. Just wondering why things are the way they are.
Moving on to a related topic; what makes Smash unbalanced? I've heard about the fact that speedy characters on large levels have definite advantages, but are there really no counters at all?
This is a chicken and the egg argument, sort of. Did the veterans influence the rules to best fit them or are these veterans so successful because they've been playing under these rules for longer. I think its the latter. The rules have been slowly evolving for years and the players with them almost simultaneously. The slight rule modifications that have happened over the years though have almost never disrupted the top players, is usually the players of moderate to almost high level skill that get most effected (say, the elimination of a counter stage that some players relied on to win matches).
In Melee, Fox on Hyrule is the easiest example of the problem I think you are describing. When there was a loop on a level, you could not corner a faster opponent like you could on a standard platform stage. Without the ability to corner a faster character, slower characters would simply be unable to make up percentage leads for no other reason than they would not be able to catch the faster character. Does this mean the game is imbalanced? I don't know, depends on what you factor into balance. On a standard random/neutral stage, in Melee, the game was relatively balanced (about 1/4th the cast still viable), yet, since the rules are structured with counter stages (to encompass a greater required understanding of both characters and levels), this list expands to between 1/2 and 3/4ths of the characters still being viable. Sure, some characters were piss poor, but the somewhat poor characters could choose levels that play to their advantage and make them more powerful characters.
For Brawl it is still to early to tell how the characters stack up against each other. Most people seem to think MetaKnight/DeDeDe are near the top. I agree with this, but as a Diddy player I have yet to find a strategy/tactic with a single character that cannot be countered by just using banana's, and this includes camping. Does that mean Diddy is near the top? Certainly not, he simply can't kill people as effectively as some characters, but it does mean, at the very least, no strategy (at least on platform stages) will through me for such a loop that a match is not winnable. These are the nuances that will have to be considered, along side the results we see from tournaments, for determining the overall balance of the characters in relation to each other. Tiers do and will exist in Brawl, its just the nature of fighting games, but we can always hope that enough counters between characters exist that no character can singularly dominate the competition.