Since the release of Pokémon Sword and Shield, one mystery has revolved around the actual effect of the Catching Charm. The Catch Charm was added to the Pokémon series this generation, but not much has been known about its effect other than the description given by the item:
Holding it is said to increase the chance of getting a critical catch. Curiously, the charm doesn’t shake much.
Well, thanks to work done in collaboration with Anubis by looking at the game code, we now know what it does. It doubles the critical catch rate if you own it.
Here’s the relevant logic if you want to see for yourself:
A critical capture is a mechanic added to the games a few generations ago where the game only lets the Poké Ball shake once, instead of three times. You hear a higher-pitched “whoosh” when the ball is thrown, and then the ball hovers in the air for a second and then does a single, larger-than-normal shake. This increases your chances of catching the Pokémon on that throw significantly.
The game first calculates a value called here as the “final catch rate” which takes a look at the maximum HP, current HP, and base catch rate of the Pokémon, as well as its status condition and which Poké Ball you’re throwing. That value is then fed into a formula to determine the value called “critical rate:”
critical_rate = floor(min(final_catch_rate, 255.0) * pokedex_mod / 6.0)
This critical rate is then compared to a random number between 0 and 255 and if that random number is smaller than the calculated critical rate, the game attempts a critical catch.
The chance of triggering a critical capture already rises with how many Pokémon you have registered in the Pokédex. If you have fewer than 31 then you will always have a 0% chance. On the other end, having more than 600 multiplies the chance by 2.5.
Now, in Sword and Shield they’ve now added a charm that doubles that effect. Here’s a plot that I made showing how your chances are increased with the charm. The x-axis shows the base catch rate that a Pokémon could have (a value between 0 and 255 that indicates essentially how easy the Pokémon is to catch) and the y-axis is the chance that you’ll trigger a critical catch.
As you can see, your chance at getting a critical capture doubles even if the Pokémon is at full health with no status conditions. The value that gets doubled is the final catch rate before it is passed to that minimum function, so it raises the maximum chance of getting a critical capture (if the Pokédex has the highest possible modifier, you’re using a good ball, and have weakened the Pokémon via damage and status conditions) from about 40% to a little more than 80%.
Another side effect of the charm has to do with Poké Balls that have a very low chance of capture. The Beast Ball offers a “bonus” of 410/4096 (about 10% as effective as a Poké Ball) when thrown at any Pokémon not classified as an Ultra Beast. When attempting to throw it at a Pokémon with full HP, there are many base catch rates that would result in a 0% chance at a critical capture no matter how many Pokémon you have in your Pokédex.
Here’s a visualization that shows this effect in action. Again, the x-axis shows all of the possible base catch rates the Pokémon could have, while the y-axis shows the chance at triggering a critical catch. The different colored lines also show how the Pokédex modifier (“mod” in my legend, a value between 0 and 2.5) affects your rates as well. This was done for a Pokémon at full HP with no status conditions when using a Beast Ball.
Now, if we apply the catch charm to all of those same calculations, we get the following visualization.
Not only are the chances doubled, but we can see that the possibility of getting a critical catch has shifted to lower base catch rates. The major reason why this happens is that the game rounds down the critical catch value (in the formula above). This is also why we get all of those jumps in the chances in the plots.
A really neat side effect, though not very many people are going to be throwing a Beast Ball at a Pokémon with full HP. This is more to illustrate the effect of the Catching Charm at the extremes.
So, there’s a deep dive on the effects of the Catching Charm. Here at Shiny Hunter Club, we have a calculator that can help you figure out your chances at catching a Pokémon. I will be adding the effects of the Catching Charm very soon to the calculator, so look forward to that very soon.