One of the main gameplay elements of Pokemon Go is the resource management subsystem. In order to do a lot of things in the game you need resources, such as pokeballs to throw at wild pokemon so you can capture them and add them to your collection. You gain most items by visiting pokestops, real-world locations where you can “spin” the pokestop to get a random selection of items, and once you spin one you can't spin it again for five minutes. Since you need items to keep playing it encourages you to travel around to different pokestops, and in the process of traveling around you tend to encounter wild pokemon, which you then try to capture, using items, so you need to go to more pokestops, etc. At the basic level this is a pretty solid gameplay loop.

Different types of items

The most common items are the pokeballs, which come in normal, great, and ultra varieties, which have progressively greater odds of capturing a pokemon. If you encounter a really rare or really powerful pokemon it's nice to have an ultra ball so you have a good chance to catch it. Some other common items are the berries: Razz Berries are one-time-use items that improve your capture percentage when you throw a pokeball and Pinap Berries give you more “candies” when you capture a pokemon (which you can use to evolve them, when you save up enough). You also tend to collect a lot of potions and revives at the pokestops, which are useful for patching your pokemon up after they've battled in a gym. The more powerful potions are less common than the weaker ones, and the same with the pokeballs.

Evolution items

Normally, when you want to evolve your pokemon from a more basic form to a more advanced one you just need enough of the specific type of candy they need. But in the 2nd generation of pokemon the introduced “evolution items”: if you want to evolve your Scyther into a Scizor you don't just need 50 Scyther candies, you also need a “Metal Coat” item. You can get evolution items extremely rarely from pokestops, although you're guaranteed to get one from your first pokestop of the day if you spin at least one pokestop per day for seven days in a row.

Raid items

Some items can only be acquired by beating a Raid Battle boss. These are powerful pokemon that occasionally show up for limited times at gyms. When you beat them you can get Rare Candies (candy that you can convert to any type of pokemon-specific candy), Golden Razz Berries (extra-powerful one-time-use catch-rate increaser), and Technical Machines, items that let you change a pokemon's moves.

Store items

Some items need to be bought from the in-game store using pokecoins (which you can either earn by defending gyms or buy with real-money transactions). Things like Incubators (to hatch pokemon from eggs you sometimes get from pokestops) or Lucky Eggs (temporary XP gain boosters) are like this. Sometimes the store will offer these things as part of “package deals” when there are special events running.

Many are “too good to use”

Because they are so rare, I always feel reluctant to use my more powerful items. For example, because I rarely fight in raid battles I'm reluctant to use Golden Razz Berries unless I'm trying to capture a really special pokemon. Because it's so powerful and useful I always feel like I ought to save it for the future. But since I feel like that every time I rarely end up using them at all. So, ironically, these “rare” items are taking up space in my inventory but rarely doing me any good. It's like having an attic full of collectors' items you'd never be willing to sell – theoretically valuable, but in practical terms just preventing you from using your attic for anything useful.

I hate throwing things away

I have an aversion to throwing away perfectly good stuff, and that seems to extend to Pokemon Go items, too. Even though I tend to have more basic pokeballs and razz berries than I use it feels so “wasteful” to just delete them from my inventory that I tend not to do it.

So my inventory fills up

The consequence of that is that my inventory of items tends to fill up. And when your inventory is full you can't spin pokestops. So the consequence of not being able to spin pokestops is that I tend to keep my phone in my pocket and be less engaged with the game. Which seems like it's not an ideal situations from a game-design perspective! It's true that I can buy upgrades that increase the size of my inventory in the store, but that would cost pokecoins, which are themselves a scarce resource.

I can probably just bite the bullet, but...

The “solutions” to these “problems” are somewhat obvious for me to implement, just pay for the storage upgrades and trash some of my low-value items. But because this is supposed to be fun I hate having to use willpower to force myself to do this kind of stuff. It would be much nicer if I could limit the amount of some of these items that stack up in my inventory, it's a lot less psychologically taxing to say “I don't want any more basic revives” than it is to say “I want to throw some of the basic revives I have into the garbage”. It would be even nicer if there was some mechanic in the game that served as a better “resource sink” that I could use these items on, so I didn't feel like I was throwing them away. (You can use some of them that way, such as by feeding berries to pokemon that are defending gyms, but for things like the evolution items I feel like I'd regret throwing any away if it turns out I need them later).