I mentioned months ago that using equipment to tweak balance to certain "competitive" preferences would be a valid idea. No one seems to want to have to do anything past unlock characters, though. Any extra work is obviously not an innate part of the game, and shouldn't be considered for competitive reasons >.>
Suppose that it was somehow universally agreed upon that a character deserves +10 def and +5 speed. Let's pretend that everyone in the world actually agrees on this, and somehow it is psychically communicated to all players of smash present and future that this is the case.
We
still can't do it, because you could play single player for a year straight and still not get that exact set of equipment modifications.
Additionally, setting it up on every single station for every match would be obnoxious. Unlike custom moves, which are always the same and in the same location, item sets--even if everyone had them--are going to be in random locations. Actually sitting down and figuring out if a station even has that exact combination of equipment is actually np-hard.
*****
Every smash release, we have people proposing radical rules that can't possibly be adopted because they are
insular. This means they can't be used because they
actively prevent people who don't know about them from participating.
Suppose you and your friends show up to a tourney, and everyone has
Increased Walking Speed equipment, and they are playing on
1.1x knockback. How on earth were you supposed to know about this? Who could have predicted or guessed this? How on earth were you expected to have reasonable practice with these weird house rules?
Such house rules are not like Stock vs. Time or 2-stock vs. 3-stock, since they actually affect gameplay. They are also unlike custom moves, items, or team attack, because they are not
discrete; it is just as reasonable for those things to be off as it is on.
"This tourney is 3-stock, 8-minute, with these legal stages, custom moves, and team attack." - all perfectly normal binary options right there in the rules menu.
"This tourney requires everyone have a +16 Atk -28 Def Decreased Landing Lag badge, a +75 Atk -11 Def Weakened Dodge Ability badge, and a +7 Spd -19 Atk No-Flinch Charged Smashes badge." - what? You can't be serious. This reads like a Monty Python skit.
At that point you are no longer playing the base game by any interpretation, you are playing some weird subjective set of house rules.