The Upgrade Item in Pokemon GO
The upgrade item in Pokemon GO is a special evolution item that can help certain creatures in your pocket increase their power. It's an essential bridge to mastering evolution and expanding the Pokedex.
Players can purchase upgrade items by spinning Photo Disks at PokeStops and Gyms for seven days in a row and through events-specific Field Research tasks. However, these items have a low rate of dropping.

Porygon2 can be evolved using this item
In Pokemon Go players can make use of a special item called the Upgrade to transform certain Pokemon into their more powerful forms. The process involves a few steps, but it's not difficult to do and provides an additional dimension to the game's gameplay.
Porygon is one of the most unique Pokemon in the Pokemon series. It can be evolved to Porygon2 or Porygon-Z. To unlock these evolutions, you'll need to have a few things. These include the Upgrade disc and Dubious disc. These items are scarce, but they are not impossible to find in the game.
The Upgrade is a scarce item that can be used to unlock the second stage of evolution for Pokemon Porygon in Pokemon GO. To obtain this item, players must capture and transfer a Porygon. It is recommended to capture as many Porygons possible. Each capture and transfer will result in one Candy. Trainers can try to obtain this item by spinning PokeStops. They have a chance to drop the item, along with other rewards.
The Dubious Disc is another rare item in Pokemon GO that can be used to evolve Porygon into a more powerful form. To obtain this item, players need to collect 50 pieces of Porygon Candy. This can be achieved by catching Porygons, then transferring them Professor Willow or walking with your Pokemon as a companion. Trainers can also spin PokeStops to try and hit this item, but it's a bit more difficult.
Transforming a Porygon into a secondary form is a fun process that adds some depth to the Pokemon GO experience. It's not difficult to do however, you'll need some special items and in-game money.
Porygon, unlike most Pokemon in the series, can only evolve into its final form using an item known as Upgrade. This item is incredibly rare and can be found by spinning PokeStops or working on Research Breakthroughs. You can also obtain the item if you trade a Porygon with the item attached, or if you use a Special Trade item.
It is a Tier 4 exclusive drop
Upgrades are items that can be used to enhance equipment, by adding new attributes. Upgrades can be found in the inventory of the game, from karma sellers, or as rewards for events that are special. They can be added to weapons, armor, trinkets, and gathering tools. Upgrades can be added to any slot on an item. Some upgrades require that an item of higher quality be added. Most upgrade components can be replaced, however, it will damage the previous one. Only a handful of upgrade types can be salvaged using high-tier salvage tools, for instance Black Lion Salvage Kit or Ascended Salvage Tool.
Items can be upgraded by combining an upgrade item with the item it is placed in, or rerolling it using a reroll token. The rerolled item will have the same stats as the original however it also has a new tier and level. Every item has an upgrade level maximum and a minimum level. The rarity and level of the item determine the level. Each tier is broken down into three levels, and each level has its own cost for upgrades and bonuses.
Generally upgrading an item will increase its primary stat by a predetermined amount, and will also give an extra stat that is random. As the tier of an item increases, the cost to upgrade it will increase. However there are discounts on certain items and with each step the number of upgrades needed will decrease.
The upgrade item is obtained by spinning Photo Discs in PokeStops or Gyms. However it has a low probability of dropping each day. It can also be obtained as a reward for a seven-day streak of spinning at least one PokeStop or gym Photo Disc each day, and through specific research tasks for events.