[Ambicrow3]

Ya, I agree the team is quite weak to a bunch of general stuff, but it was just an example of how a team would look like, because expressing thoughts through a team may be easier to see than a good description for some people. Also, statistically speaking, you are right, the example team is hilariously weak to stuff, but you got to remember to that after you have tricked a couple items back and forth, the match-ups are different. I believe that most teams centered around items will look weak to common threats on paper, but are easily handled do to the hazardous items that they will obtain. For example, you say the example team would like a reliable spinner. When used in practice, this team will only switch in the sweepers once, and if done correctly, it is game over. That is pretty much the strategy. get to a point in the match in which your sweeper is facing a choice locked resisted move. From there it is done. Just clean with another pokemon if he dies, and you win.

Now back onto the topic at hand.

I believe there are so many items that can effect a pokemon, as each pokemon needs an item to work at its optimum. For example, is Chansey better with a eviolite or a choice scarf? That one was is quite obvious. But, let's take a harder question. What is better on Genesect, Choice Scarf or Expert Belt? Well, there is no real obvious answer, since it depends on what you need. Just from that example, you can see how important items can be. items decide what the pokemon is used for, and if you just laxly put items on pokemon, like a bunch of leftovers on a stall team, it may not work at its best. Maybe a pokemon is better with a shed shell, so your team isn't weak to sun? Maybe some type of SE damage reducing berry is needed, so you can surprise kill a counter. I find it sad the lack of thought in items nowadays among the new competitive battlers. If you look at experienced competitive battlers, you can see their item usage is more spread out, taking on items from every angle to find the perfect fit for their team. The best example that quickly comes to mind is Lavos Sun's Xatu. Lavos Spawn is a very respected battler, and he makes great use of Rocky Helmet on his Xatu. Realizing his team could not beat a Dragonite if its multiscale wasn't broken, he added Rocky Helmet to lessen this problem to a great extent, allowing other pokemon to kill it. As you can see, having a great knowledge of the items at hand can make an "ok" team into a great team.

PS. @Masamune-Sableye is great for balanced Item Abuse teams, or just as a general core component that could be devastating on a regular team, that would lack the team coverage to handle such threats that could avoid SE damage from your sweepers.