List of Research Breakthrough rewards

Listed below are the previous Research Breakthrough rewards:
 * 3000x XP
 * , which is either:
 * or.
 * or.
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Current month
From December, 2020, 9:00 PM UTC until January , 2021, 9:00 PM UTC

List of Pokémon encounters
Bellow there is full list of Pokémon encounters from Research Breakthrough from 2018 to 2020.

2018
From April until May, 2018, 8:00 PM UTC

From May, 2018, 8:00 PM UTC until June , 2018, 8:00 PM UTC

From June, 2018, 8:00 PM UTC until July , 2018, 8:00 PM UTC

In July, 2018 for the first time there was non-legendary Pokémon encounter available from Research Breakthrough, also for the first time it was Pokémon with exclusive move. From July, 2018, 8:00 PM UTC until August , 2018, 8:00 PM UTC

From August, 2018, 8:00 PM UTC until September , 2018, 8:00 PM UTC

From September, 2018, 8:00 PM UTC until October , 2018, 8:00 PM UTC

From October, 2018, 8:00 PM UTC until November , 2018, 8:00 PM UTC

From November, 2018, 8:00 PM UTC until December , 2018, 8:00 PM UTC

In December, 2018, there was pool of various Pokémon added as Research Breakthrough that rewarded with one random encounter instead of guaranteed Pokémon featured for specific month. From December, 2018, 8:00 PM UTC until January , 2019, 8:00 PM UTC

2019
From January, 2019, 8:00 PM UTC until March , 2019, 8:00 PM UTC

From March, 2019, 8:00 PM UTC until May , 2019, 8:00 PM UTC

From May, 2019, 8:00 PM UTC until July , 2019, 8:00 PM UTC

From July, 2019, 8:00 PM UTC until September , 2019, 8:00 PM UTC

From September, 2019, 8:00 PM UTC until November , 2019, 8:00 PM UTC

From November, 2019, 8:00 PM UTC until January , 2020, 8:00 PM UTC

2020
From January, 2020, 8:00 PM UTC until February , 2020, 8:00 PM UTC

From February, 2020, 8:00 PM UTC until March , 2020, 8:00 PM UTC

From March, 2020, 8:00 PM UTC until April , 2020, 8:00 PM UTC

From April, 2020, 8:00 PM UTC until May , 2020, 8:00 PM UTC

From May, 2020, 8:00 PM UTC until June , 2020, 8:00 PM UTC

From June, 2020, 8:00 PM UTC until July , 2020, 8:00 PM UTC

From July, 2020, 8:00 PM UTC until August , 2020, 8:00 PM UTC

From August, 2020, 8:00 PM UTC until September , 2020, 8:00 PM UTC

From September, 2020, 8:00 PM UTC until October , 2020, 8:00 PM UTC

From October, 2020, 8:00 PM UTC until November , 2020, 9:00 PM UTC

From November, 2020, 9:00 PM UTC until December , 2020, 9:00 PM UTC

From December, 2020, 9:00 PM UTC until January , 2021, 9:00 PM UTC

Trivia

 * As with Pokémon encountered as a reward for completing a Field Research task, Pokémon encountered for completing a Research Breakthrough will be level 15.
 * The Pokémon encountered in Research Breakthrough is not set when you start the week. If you hold off obtaining the last stamp and Breakthrough, it is possible to wait till the encounter Pokémon changes to immediately obtain the new Pokémon available.