To obtain the entry in the Pokédex for each Pokémon, you must reach Level 10 research level in the device. This level is only counted up to Level 10, as this is the level at which you get a full entry in your Pokédex. when you complete all the research tasks for a Pokémon, you will increase your chances of that Pokémon appearing as a shiny, although there are better methods to get those coveted shiny Pokémon.
How the research tasks levels work
As we have mentioned before, you only need Level 10 in the Pokémon to count as an entry in the Pokédex. You can see the research level by opening the Pokédex (down arrow) and selecting the Pokémon you want to see. This appears at the bottom right as shown in the image.
How to obtain and count the research Level 10
When you want to obtain the Pokédex entry of a Pokémon, you must see the research tasks that this Pokémon has. To do this you can open the Pokédex and select the Pokémon manually, or if you have the Pokémon in front of you players can press the ZL + button below to see these tasks.
Each task has different levels, among many others, the most common of which is the capture task. Each box you complete will count as a research level and if the task is marked with red arrows, each box obtained will count as two levels. Once players get to Level 10, they will have the entry of the Pokémon in the Pokédex. Here is an image so you can understand it better.
What happens if I get the tasks and I have not captured the Pokémon?
The tasks will be counted but will not count as an entry in the Pokédex until you capture the Pokémon. In the following image you can see a Haunter at Level 0 although it has already achieved some tasks.