Capturing Pokémon is the most important thing in the Pokémon Games. Without it you wouldn't be able to obtain any Pokémon other than your starter. In lamens terms, essentially what you need to do is weaken the Pokémon, pick a PokéBall and throw. However things are much more complicated that that when you get into the code. Of course, if you're using a Master Ball, none of this counts.

There are many deciding factors to the capture of the Pokémon. These include that Pokémon's Maximum HP, Current HP, Status Ailment and it's Catch Rate. The Pokémon's Catch Rate is a number between 0 and 255, the higher the better. You can see the Catch Rates for the Pokémon in our Pokédex.

The formula for determining the capture of the Pokémon is as follows:

Catch = PokeballEffect (((( 4 * Max HP - 2 * HP ) * Catch Rate ) / Max HP ) + Status + 1 ) / 256

Now the Maximum HP and Current HP of the Pokémon that you are about to catch are obviously not known by you, however that is what the colour coding is for and really the lower the level the better the chance. If however the HPs are over 255, then they are divided by 2 and then by 2 again and placed into the equation as such once rounded down to the nearest digit.

Status Ailments are a completely different amount however. Here is a small table stating the Values that each of the Status Ailments is given

Status	Figure
Frozen	10
Sleep	10
Paralysis	5
Burn	5
Poison	5
None	0

Now this does have a major effect on the capture and could definately be the difference between capturing the Pokémon.

The final element of capturing Pokémon is the type of Pokéball that is used. Each of the Pokéballs either Multiply or add to the figure before the final division of 256 is done in order to determine the final amount. Below are the Pokéballs and their effects and the amount they actually alter.

PokéBalls

Icon	Name	Effect	Fig.
	PokéBall	Standard ball used to capture Pokémon	* 1
	Great Ball	A Ball with a better catch rate than a PokéBall	* 1.5
	Ultra Ball	A Ball with a better catch rate than a Great Ball	* 2
	Master Ball	A Ball that never fails at capture	---
	Safari Ball	A Ball that only exists in the Safari Zone	* 1.5
	Net Ball	A Ball that works better on Bug or Water Types. If they aren't Bug/Water then * 1. If they are then * 3	* 1 * 3
	Dive Ball	A Ball that works better on the ocean floor. If used out of water then * 1. If battle field is underwater then * 3.5	* 1 * 3.5
	Nest Ball	A Ball that works better on Pokémon of a lower level The Opponent's Level is put into the following formula: (40 - Level)/10. The higher number at the end the better	* 1 to 3
	Repeat Ball	A Ball that works better on Pokémon previously captured. If the Pokémon hasn't been in your Pokédex then * 1. If it has then * 3.	* 1 * 3
	Timer Ball	A Ball that works better the longer the battle has run Runs off a formula based on how long the Pokémon has been in battle: (Turn + 10) / 10. The longer the better (Maximum of 40 turns to count)	* 1 - 4
	Luxury Ball	A Ball that can make a Pokémon like you easier. The Pokémon gains an extra Happiness Value for each Happiness Value that has been obtained	* 1
	Premium Ball	A Ball that is given at special events.	* 1
Balls only in Sinnoh
	Dusk Ball	A Ball that makes it easier to catch wild in dark places like caves caves and at night	* 4 * 1
	Heal Ball	A remedial Pokéball that restores the caught Pokémon's HP and eliminates any status problem.	* 1
	Quick Ball	A Pokéball that provides a better catch rate if it is used at the start of a wild encounter Capture Rate lowers every 5 turns by 1 point	* 4 - * 1
	Cherish Ball	A Pokéball used to signify special Pokémon	* 1
Balls only in Johto
	Fast Ball	A Ball that catches Fast Pokémon If the Pokémon does not have a high Speed then * 1. Else * 4	* 1 * 4
	Friend Ball	A Ball that makes Pokémon like you The Pokémon's Base Happiness is 200 instead of 70	* 1
	Heavy Ball	A Ball that catches Heavier Pokémon Easier If the Pokémon is Less than 220lbs then -20, Between 220lbs & 440lbs then +0, Between 440lbs & 660lbs then +20, Higher than 660lbs + 30	-20, +0, +20, +30
	Level Ball	The bigger the difference in level between your Pokémon and the Capture Target, the more likely the capture If the Pokémon's Level is greater than the opponent's level then * 2. If half your Pokémon's Level is greater than the opponent's Level then * 4. If a quarter of your Pokémon's Level is greater than the opponents Level then * 8	* 2, * 4, * 8
	Love Ball	This ball works better on Pokémon of the opposite Gender If the Pokémon's Gender is not the same as the Opponent then * 8. If it is the same or either have no gender then * 1	* 1 * 8
	Lure Ball	This ball works better on Pokémon snagged with Fishing Rod If the Pokémon was obtained through Fishing then * 3. If the Pokémon wasn't, then *1	* 1 * 3
	Moon Ball	This ball works better on Pokémon that evolve with Moon Stone If the Pokémon evolves with Moon Stone then * 3. If the Pokémon doesn't, then *1	* 1 * 4

And thus with this you are able to make the calculation. What you should get will be a decimal number which is essentially a percentage. The higher the percentage, the more likely you are to capture it. If the number is above 1 then you should get the Pokémon immediately