Pokemon-go – How to prevent CP 3000+ pokemons from losing motivation unreasonably quickly

There's an Android app called PokeGo Master which comes with an Arc overlay. Using it, you can simply enter your current Trainer level and move the arrow around until the black circle on it perfectly covers the white circle of the actual arc. As long as the Pokemon view screen is scrolled all the way up and Trainer level is entered correctly, the overlay matches the real level perfectly using the datamined calculation for the arc's position.

The app conveniently also offers IV calculation, which is probably your intent anyway.

According to this article, which references this reddit post, and it is calculated that Pokémon lose motivation over time at:

1. ~10% MPH for Pokémon with CP >= 3000
2. ~1% MPH for Pokémon with CP < 3000

It would appear that Pokemon with over 3000 CP lose roughly 10 percent motivation every hour, while Pokemon with CP below 3000 lose about one percent motivation every hour, one gamer observer on Reddit.

While CP and motivation are not the same thing, they are connected, as losing motivation decreases a Pokemon’s CP. Just to throw out some examples of how motivation can affect CP, one Reddit user found that a 3348CP Tyranitar and a 3094CP Gyarados both lost 3CP roughly every 30 seconds; a 2800CP Blissey, a 2795CP Donphan, and a 2753CP Alakazam all lost 3CP in four minutes; and a 2409CP Dragonite lost 3CP in 4 minutes and 20 seconds.

When the Pokémon is defeated, it is calculated the motivation will drop an additional ~20%

In battle, Pokemon generally lose about 20 percent motivation every time they are defeated, meaning defeating a Pokemon five times in battle should be enough to drain its motivation.