Here's what to look for:
* A pink, teardrop-shaped icon will appear next to the Pokémon's status condition, like paralysis or sleep.
* The icon will be flickering. This indicates the presence of the Pokerus.
Here are some important things to remember about Pokerus:
* It's rare. You won't encounter it very often.
* It only lasts for 24 hours in-game time.
* It can be passed on to other Pokémon by putting them in the same box.
* The Pokerus increases the amount of EVs (Effort Values) your Pokémon gains after battles.
Tip: If you see a Pokémon with the Pokerus icon, be sure to keep it in your party or box. You can then use it to spread the Pokerus to other Pokémon by placing them in the same box.