Grandpa: Hey sonny! Watcha playin' there?
Grandson: I'm playing Pokemon Diamond.
Grandpa: DIAMOND?! Why back in my day we only had the basics! Red and Blue yep. None of this Diamond stuff. Diamond isn't even a color! An' we only had 150 Pokemon and we were happy with it!!
Grandson: But that was like only ten years ago, grandad.
Grandpa: But shut up.
Grandpa: And another thing... it wasn't so dangblast complicated. If I wanted to be the best Trainer in the world, all I had to do was beat Lance and that old coot Gary. Always did get to gyms before me that boy did. Nowadays I gotta "EV Train" and such 'n such. I didn't serve two years in 'Nam so I could care about invisible statistics and whatnot.
Grandson: But grandad, invisible stats and EVs have been around since the Red and Blue days!
Grandson: It's true! You remember those items like Carbos and Zinc and Calcium right?
Grandpa: Yeah... I never did use 'em. I just sold 'em 'cause I didn't know what they did. They fetched a pretty penny!
Grandson: Those things boosted the EVs of the Pokemon you gave them to.
Grandpa: Oh really? Tell me more.
Grandson: Well where to begin? In the game, there are all kinds of stats involved, some visible and some not. Collectively they're called Dynamic Values and they serve to differentiate all the Pokemon from one another. They come in five types: Level values, Effort Values, Individual Values, and the later games introduced Gender Values, and Nature Values.
Grandpa: Level... Values...?
Grandson: Yeah well those are the easiest; that's just another name for the level of your Pokemon. Just battle other Pokemon to get experience and that stat changes. Simple right?
Grandpa: Boy I've been leveling up Lickitungs since before you were born!
Grandson: But I'm sixteen.
Grandpa: When did you get so old?
Grandson: Since sixteen years ago. Anyway, after you level up, you know how you get those little +numbers to your different stats? Those numbers are determined by Effort Values.
Grandpa: I remember those things. I never paid much attention to that little screen since I double-tapped the A button really fast.
Grandson: Man grandad you've missed out on so much stuff. The different Pokemon you fight give out "Effort Points" that boost your stats. Whichever is their dominant stat is what they contribute an EP to. For example, a Bidoof's highest stat is its HP so fighting one of those would contribute one Effort Point to your
Pokemon's HP stat. You would have to defeat four Bidoofs to raise the HP by +1 upon leveling up.
Grandpa: Any reason to take out those dopey Bidoofs is good enough for me.
Grandson: Well there are limitations. You can't just go on a killing spree to get a super monster with like 1000 HP.
Grandpa: So it's not like 'Nam?
Grandson: Nope. Altogether your Pokemon can only get 510 Effort Values and any more won't be counted. That would make the total number of Effort Points available to gain 126. But that's waaay too much for any reasonable increase, so a limit of 255 is placed on every stat. At four points for every +1 increase, that means a maximum 63 point increase in any one area. 
Grandpa: Whoa there Sally! Slow down with all the big numbers! Gonna make me get out my calculator with the big buttons. You're sayin' I'd hafta kill 255 Bidoofs to get the most HP?!
Grandson: Pretty much. If you have the Macho Brace equipped, that number is halved since it doubles the EV yields. Pokerus does the same thing without being a hold item. And don't forget about those Vitamins we were talking about earlier. As a matter of fact, using all of those together would cut that 255 that you'd have to battle down to like 30 or 40.
has information about Pokemon that give out which EPs and how many. Like a Butterfree gives out two points for Special Attack and one for Special Defense.
Grandpa: Link? Like that green fellow with the boomerang, and the sword, and the hey listen, and the Heart Pieces, and the excuse me princess and boopity bop shamalama....
Grandson: Yeah Effort Points are kinda like Heart Pieces. 
Every four gives you a bonus unit.
Grandpa: I'm following along just fine! You don't have to dumb it down for me sonny boy. So you fight fast Pokemon and get faster, is that what EV training is?
Grandson: Basically. Serious players may put all 63 points in their Poke's best stat to specialize in those wierd terms you hear on message boards. Gyarados has Attack as its highest stat 
so someone might EV train to make it a very good Physical Sweeper. It would clean up shop!
Grandpa: You may know about these fancy systems and such but you aren't all that great at making puns.
Grandson: Yeah well you can EV train to make up for some of its shortcomings too, but some Pokemon just aren't cut out for that.
Grandpa: Like Kangaskahn? She's got that baby in her pouch and shouldn't be fighting anyhow.
Grandson: That too, but I was getting more at Individual Values.
Grandpa: What, more invisible number thingies? I didn't buy these thick glasses for fashion you know.
Grandson: Yeah well, you can use them to look at the buttons on your calculator when you try to calculate IVs. Without getting out formulas that you wouldn't understand without a few Calculus courses, I'll just say that IV's are what make stats vary in the first place. It's why every Diglett you come across doesn't have 26 HP or something. And part of why you can't just catch strong pokemon and expect to win without raising them. But part of that last one probably has more to do with EVs.
If the IVs have a very specific distribution, then you'll have a shiny on your hands. Don't get your hopes up though, there's like a one in 8000 chance of that happening. 
Grandpa: There you go again with all those big numbers 'n such. I always told yer mother that you were a smart kid, if not a little naive and lax with the chores.
Grandson: Speaking of random adjectives, that brings us to Nature Values, or Natures for short.
Grandpa: Those are the things that them youngins spend so much time trying to get that they poop in socks, right? I'll never understand your generation.
Grandson: Grandad, you're the one always talking about how you had to poop in a hole in the ground on your old farm.
Grandpa: I didn't have a choice!
Grandson: Remember how we were talking about EVs and getting the best out of your Pokemon? Natures are just another factor in adjusting stats. They essentially give an extra 10% increase to one stat when leveling up (for 110% overall gain) and a 10% decrease in another (for 90% overall gain) although there a few that give no bonuses. For instance, that Gyarados above has Attack as its highest base stat and Sp.Atk as its lowest. In that case, an Adamant nature, the one that's +Atk and -Sp.Atk 
, would be beneficial if you want all of its glorious Attack power.
Grandpa: I see.... So if the Nature took away from the Attack, it would be a hindrance. Still not worth poopin in a gym sock for.
Grandson: I'm sure they take their systems with them to the bathroom if they have to go. Or save the game. Or at least close the DS. Well that's the basics of Dynamic Values.
Grandpa: That wasn't so hard to understand after all! Even with my old noodle, I still got most of it. Wait... didn't you say there were five? That only felt like four!
Grandson: Oh yeah, there are Gender Values too, which is just male and female. If it has a lower Attack IV, the Pokemon will be a girl. If not it's a boy. This doesn't count for single- and non-gender species, obviously. The GV also determines what moves they'll pass on during the breeding process.
Grandpa: They become women if they have lower Attack? That sounds like sexism.
Grandson: But grandad, didn't you grow up in the 40s?
Grandpa: Heh heh, don't you forget it.
Information about IV formulas for the mathematically inclined: http://www.serebii.net/games/ivs.shtml http://bulbapedia.bulbagarden.net/wiki/Individual_Values http://bulbapedia.bulbagarden.net/wiki/Hidden_Power_calculation
Gender Ratios: http://bulbapedia.bulbagarden.net/wiki/List_of_Pok%C3%A9mon_by_gender_ratio
General DV information: http://www.serebii.net/games/dvs.shtml
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