As any great battle master knows you must be prepared with the best items and skills to hand to defeat the enemy- and Pokemon Unite is no different!
Pokemon Unite has Held Items which allow you to give your chosen Pokemon an advantage over others during a battle. To upgrade those items players must first reach Level 9 and also own Item Enhancers.
Item enhancers are available as in-game rewards by completing missions, in Energy Rewards, and at the Aeos Emporium and can be purchased with Aeos Tickets. Aeos tickets can be earned in-game as rewards for progression and in the battle pass.
Once you have your Item Enhancers and are at Level 9 or above, go to the Menu, and find Battle Prep. There you will find Held Items where you can select and offer your Pokemon the Held Item of your choice. Go to All Held Items and select the item you need to upgrade.
Each time you upgrade an item it increases in usefulness, eventually getting to the point where it has doubled in effectiveness. With each upgrade, player will need to spend more Item Enhancers so always come prepared!