Hidden Numbers
You may have noticed that no 2 Pokemon are exactly alike; for instance, go and catch three Zigzagoons or Rattatas. You'll notice that one may have higher speed, defense or both. Or neither. One might be a boy, while the others are girls. One might have a Sassy nature, or Hardy, or Timid. It is nearly immpossible to have two identical Pokemon without cheating (The cloning trick in Crystal and Emerald, for instance). This guide explains how that happens.
Hexadecimals
The most important number is the hexadecimal. When a Pokemonis required, a hexadecimal will pop up. Then, your game takes all the respective information and uses it to make a Pokemon. For instance, in Red/Blue/Yellow, Mew's hexadecimal is 21 (in base 10, the numbers you use to count). Many "glitch" Pokemon like Missingno. are just hexadecimals without actual Pokemon in them.
DVs or IVs
The next set of numbers is DVs (Deter Values) or IVs (Individual Values). It doesn't matter what you call them; they both mean the same thing. When ever you recieve an egg or see a wild Pokemon, it is assigned a set of IVs, one for each stat. Each IV can be anywhere between 0 and 31. IVs help determine stats, Hidden Power's type and strength, and in Gold/Silver/Crystal, they also determined gender and wether or not it was shiny. Psypokes has a calculater that tells Hidden Power if you know the IVs. These are the second most important numbers, with hexa decimals being the most important.
Effort Values
Effort Values, or EVs for short, help determine stats (along with IVs). Whenever you defeat a Pokemon, wether wild or trained, the Pokemon who defeated it will gain EVs. For instance, if Pikachu defeats a Pidgey, he gets one Speed EV. Each Pokemon can have 510 EVs combined, and only 255 in any one stat.However, the real maximum is 252, because every 4 EVs will raise the stat in question by one. That means, that it won't go any higher or lower, but you'll stiil have 6 extra EVs to put in another stat.
