If you've ever played any kinds of role playing games in your life, your probably aware of the concept of "experience points", often abbreviated EXP. These points are also presesnt in the Pokemon games and are one of the most obvious game mechanics. By fighting and winning battles, Pokemon will grow stronger by obtaining these experience points and reaching the next level of growth. The game designers of Pokemon, however, found ways to make this common mechanic more complex as well.
Pokemon grow at different rates, there is no surprise there. Its always taken more time to raise that Dragonite another level than it takes to tame that tiny Caterpie. This is all due to "Growth Rates". Each and every Pokemon is assigned a growth rate and this rate effects how fast or slow the Pokemon levels up. The growth rates are as follows:
Very Short 600,000 experience
Short 800,000 experience
Regular 1,000,000 experience
Irregular 1,059,860 experience
Long 1,250,000 experience
Very Long 1,640,000 experience
So how do we know that these are the set number of experience needed for each Growth Rate? Well, its all because of the Growth rate formulas. Each growth rate has its own formula in the games coding. For those that wish to know they are as follows: (Note: The formulas for Very Short and Very Long are still unknown to the public)
Short .8(Current Lv.)^3
Regular (Current Lv.)^3
Irregular 1.2(Current Lv.)^3 - 15(Current Lv.)^2 + 100(Current Level) - 140
Long 1.25(Current Level)^3
The last bit of this game mechanic to cover is the actual formula of gaining experience.
Experience = ((Base EXP. x Lv.) x Trainer x Wild)/7
And now let me explain these variables in greater detail, from left to right. Just like each Pokemon has a set number of base stats in strength, defense, etc., each Pokemon also has a number for "base experience". The Level is obviously the level of the pokemon your facing. Trainer applies to your Trainer ID. If the pokemon your using is the exact same Trainer ID as your own then the variable is equal to one. If the Trainer ID is different than the variable is 1.5. This is why Pokemon recieve boosted experience when traded. Wild works in a similar fashion. If the Pokemon your fighting is a random pokemon you stumbled across then the variable is one. However, if your fighting a trainer's Pokemon then the variable is equal to 1.5. This is why trainer pokemon give you more experience than those found in the wild.
~Hiddenzbu