How Hidden Power Works

Hidden Power is a move with 15 base power that is currently available to 6 Pokemon: Porygon, Porygon2, Starmie, Togepi, Togetic and Unown. The game_master lists Hidden Power as a normal type move but its type actually varies. Because of this, GamePress conducted a survey to investigate this move. Thank you to everyone who provided data for this study!

Background

In the main series games, Hidden Power can take on one of 16 types based on a Pokemon's IVs. It cannot be Normal type or Fairy type. Based on this, we wanted to investigate 2 questions:

  • Can Hidden Power be any of the 18 types?
  • Do IVs determine the type of Hidden Power in Pokemon GO?

Our results suggest that the type of Hidden Power that a Pokemon gets is unrelated to anything observable.

While our results also suggest that Fairy and Normal type hidden powers are available, we are still looking for stronger evidence of this. If you have a Pokemon with a Fairy type Hidden Power, check out this contest.

Analysis

As of Feb 23, we had 923 observations. First, we removed responses clearly put in by trolls (those containing nonsensical text in short answer responses). We also removed several responses that could have been trolls or people who were not paying attention when responding (extreme outliers for height/weight or putting in a shape for Unown when the Pokemon was not Unown). We ended up with 909 reasonable responses to use in the analysis.

You can see a table of the results by clicking here. From the table, it seems that 17 of the Hidden Power types are available to any Pokemon. However, only Togepi can have a Fairy type Hidden Power. Binomial tests show that the result with fairy typing would be highly statistically unlikely assuming that all Pokemon have an equal chance of any Hidden Power. Note that we did not get any responses for Hidden Power Flying and Grass for Porygon or Hidden Power Normal for Togepi. This could be due to sample size or inability to actually obtain those possibilities.

Next, we went to test if IVs are related to Hidden Power. From the data, we found many examples of Pokemon with identical IVs who had different Hidden Powers. There were even examples of the 'same' Pokemon where the height, weight, level at capture and shape in the case of Unown were identical but Hidden Power was different. This is in line with observations by u/Leoazu. Therefore, we conclude that Hidden Power type is not related to any observable characteristic of the Pokemon.

Limitations and Future Research
Togepi

From our data, we know that the level of the Pokemon at catch (or hatch) and IVs do not determine the type for Hidden Power. It is possible, however, that Trainer Level at the time of encounter interacts with the unique spawn ID to determine Hidden Power. This will require experimenting with multiple trainers to test. Another issue is that surveys can have trolls and response bias problems. Given that there is other evidence for IVs not determining Hidden Power, we think it is not an issue for this finding. However, if you have any Pokemon with a Fairy-type Hidden Power (Togepi or otherwise) or a Pokemon with a Normal-type Hidden Power, please share with us in the comments section. Since only Togepi was reported as having Fairy-type Hidden Power, we believe that some respondents may have mistakenly filled out the survey using the Pokemon's type as opposed to the move's type.

Miscellaneous Info: TMs, identical spawns, etc
  • Since this article was written, TMs were added to the game. It has been confirmed that TMs cannot change the type of hidden power. Using a TM will just switch back and forth to the type which the pokemon started with.
  • According to this post, evolving a pokemon can change the type of hidden power.
  • Posts in the comments of this article suggest that identical spawns can give different hidden power types - however, it is not yet known whether trainers of the same level (or trainers both at least level 30) get the same hidden power type.
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