What do the symbols above a Pokemon's head mean? [duplicate]

Solution 1:

Referring to this article, those symbols are related to the catch bonus medals added to the game not long ago. When the symbols appear, they indicate that they are giving you a bonus for that particular encounter with the Pokémon.

In the screenshot below, you can see that the medals (at the very top middle) in affect are the normal medal, and flying type medal.

Another user asked before "How does the new catch bonus work in Pokémon Go?" The best answer said that the medals increase your chances of capturing other Pokémon of that type. In short, it goes like this:

• For capturing 10 Pokémon of a given type (bronze badge): +1 bonus catch rate
• For capturing 50 Pokémon of a given type (silver badge): +2 bonus catch rate
• For capturing 200 Pokémon of a given type (gold badge): +3 bonus catch rate

From this answer.

There is more that is factored into catch bonuses, but I don't want to get into it further since it is a separate question, and we have already answered it. If you would like to know more, see that question itself.

Solution 2:

These are the Pokemon's types, or more specifically, the medals you have earned corresponding to the Pokemon's types. Notice they will have differently colored borders that indicate whether you have no, the bronze, silver or gold medal of that type, corresponding to the color you can see if you view your medals by tapping your portrait and scrolling down.

As for what they do, they are merely visual indicators of any potential catch bonuses you have thanks to your medals. If you have a bronze medal, you will get a +1 catch bonus (it's unclear what that means exactly), silver gives you +2 and gold +3. In the case of dual-typed Pokemon, which show 2 type symbols on the top when you encounter them, your bonus will be the average of the 2 bonuses for each type. For example, if you have a gold medal for Normal type and a silver medal for Flying type, your catch bonus for Pidgey (Normal/Flying) will be +2.5. The visual display lets you know what bonus applies to this encounter.