Happiness is an important feature which allows some Pokemon to evolve in Pokémon in Vortex.
While there is no way to track the exact happiness points of a Pokémon you are training, you can see hearts will start to appear in the Pokémon's information when you click it's name to open the Pokédex which will go up in increments of one as the Happiness level is raised, displaying one of a maximum of four hearts: 
- Each heart needs 73 points.
- In other words, 1st heart will need 73 points, second will need 146 points, 3rd heart will need 220 points and 4th will need 255 points (max).
- All Pokémon which evolve by friendship except Sylveon need 220 points (3 hearts) for evolution.
- Eevee will need 255 Happiness points in order to evolve into Sylveon.
- Maximum number of battles which could be needed for a heart=73/1=73 battles.
- Minimum number of battles which could be needed for a heart=73/2=36.5~37 battles.
- Since the happiness points per battle is randomized (1 or 2), you would need somewhere between 37 and 73 battles in order to gain 1 heart for your Pokémon.
- Happiness is not reset when a Pokémon is traded.
Pokémon that evolve with Happiness
| Base Form | Required Happiness | Evolved Form |
 Golbat |
Level 3 Happiness |
 Crobat |
 Chansey |
Level 3 Happiness |
 Blissey |
 Eevee |
Level 3 Happiness |
 Umbreon |
| Eevee |
Level 3 Happiness |
 Espeon |
| Eevee |
Level 4 Happiness |
 Sylveon |
 Pichu |
Level 3 Happiness |
 Pikachu |
 Cleffa |
Level 3 Happiness |
 Clefairy |
 Igglybuff |
Level 3 Happiness |
 Jigglypuff |
 Togepi |
Level 3 Happiness |
 Togetic |
 Azurill |
Level 3 Happiness |
 Marill |
 Budew |
Level 3 Happiness |
 Roselia |
 Buneary |
Level 3 Happiness |
 Lopunny |
 Chingling |
Level 3 Happiness |
 Chimecho |
 Munchlax |
Level 3 Happiness |
 Snorlax |
 Riolu |
Level 3 Happiness |
 Lucario |
 Woobat |
Level 3 Happiness |
 Swoobat |
 Swadloon |
Level 3 Happiness |
 Leavanny |