I have some tips to prepare for Pokémon Go fest
1. Wear comfortable clothes that absorb sweat easily and wear running type shoes because you will be traveling far.
2. Bring a small bag that contains a power bank and charge cable, and sunscreen to protect your skin from the sun.
3. Collect as many Poké Balls, Great Balls, and Ultra Balls as possible and prepare enough Potions and Revives to keep your Pokémon healthy during the battle.
4. Determine an efficient route to pursue certain Pokémon and attend raid in the surrounding area.
5. Remove unnecessary items and transfer Pokémon you don't need to make room for new Pokémon and event items 5.