Pokemon Diamond/Pearl

Characteristics:

Like natures, characteristics help your Pokemon's stat. The Higher the IV the higher the stat will grow, here is a list(I give credit for the table to Serebii.net):

Stat	Characteristic	Possible IV Values
HP	Loves to Eat	0,5,10,15,20,25,30
HP	Often Dozes off	1,6,11,16,21,21,26,31
HP	Scatters things often	2,7,12,17,22,27
HP	Often scatters things	3,8,13,18,23,28
HP	Likes to relax	4,9,14,19,24,29
Attack	Proud of it's Power	0,5,10,15,20,25,30
Attack	Likes to Thrash about	1,6,11,16,21,21,26,31
Attack	A little quick tempered	2,7,12,17,22,27
Attack	Likes to fight	3,8,13,18,23,28
Attack	Quick tempered	4,9,14,19,24,29
Defense	Sturdy Body	0,5,10,15,20,25,30
Defense	Capable of taking hits	1,6,11,16,21,21,26,31
Defense	Highly persistant	2,7,12,17,22,27
Defense	Good Endurance	3,8,13,18,23,28
Defense	Good Perserverence	4,9,14,19,24,29
Special Attack	Highly Curious	0,5,10,15,20,25,30
Special Attack	Mischievous	1,6,11,16,21,21,26,31
Special Attack	Thoroughly Cunning	2,7,12,17,22,27
Special Attack	Often Lost in Thought	3,8,13,18,23,28
Special Attack	Very Finicky	4,9,14,19,24,29
Special Defence	Strong Willed	0,5,10,15,20,25,30
Special Defence	Somewhat Vain	1,6,11,16,21,21,26,31
Special Defence	Strongly Defiant	2,7,12,17,22,27
Special Defence	Hates to Lose	3,8,13,18,23,28
Special Defence	Somewhat Stubborn	4,9,14,19,24,29
Speed	Likes to Run	0,5,10,15,20,25,30
Speed	Alert to Sounds	1,6,11,16,21,21,26,31
Speed	Impetuous and Silly	2,7,12,17,22,27
Speed	Somewhat of a Clown	3,8,13,18,23,28
Speed	Quick to Flee	4,9,14,19,24,29

Tweaking/Hole punching
Tweaking or hole punching is a way to glitch your game. First off, this is completely harmless to your game. Just make sure you save before you do it, because your game could freeze. This can easily be done going through Solaceon town, and Jubilife city. What you do is, you ride your bike on the fastest gear while moving either up, down, left, or right. While you are doing that, you take your thumb on the D-Pad, and go around in circles very quickly. If you do it fast enough over a loading line, you could get one of four things:

A frozen game-this happens often, it just means you weren't going fast enough
An invisible wall- This is actually very cool, there is an invisible wall you can't pass, you were going faster than the previous, but not very fast
Black Void-You went pretty fast, but not fast enough, there is a big black nothingness in front of you. Here is a picture:
White void-This is the ultimate! It can have 2 versions, walkable, and unwalkable. The one you want is walkable. This means you can walk through it.

Nintendo Fanatics' Shiny Hunting Guide:
As you may or may not know, there are shiny Pokemon. This means that they are a different color. First of all, the Pokemon that you want to capture shiny using this guide must:

be in the grass(the regular grass, not the grass you can't ride your bike in)

have more than one of it's kind in your game (No legendaries)

Okay, now from experience, Pokemon that come from swarms are much easier to shiny. You can check what swarm is in Sinnoh, talk to the little girl in the house at Sandgem town once you beat the Elite Four. Once you see every Pokemon from the Sinnoh Dex, talk to Professor Oak in Pal Park, South East of Sandgem Town. He will give you an item called the Pokeradar. This will be your lifeline to capturing shines. First of all make sure you have a lot of Pokeballs, for obvious reasons. Second of all, buy plenty of super repels (you can use repels, or max repels, but super repels give you more steps for your money) you should probably buy over 150, because it could be a while. Third of all make sure you have a Pokemon that will be able to kill MANY of the Pokemon that you are going for. Okay, now to start. Walk into the grass, use a super repel, and have your Pokeradar set to the Y button, and use it. You will see the grass move. There are a few types of movement, they are as follows:

Rotating-The grass just wiggles a little
Lines-The grass has small yellow lines over it
Gold Stars- The grass has small golden stars on it
Silver/Rainbow Stars-This is the one you want, it contains a shiny, you will definitely know it when you see it

Now you are not likely to see a Silver one when you first start, so pick any of the other ones, until you find the species of Pokemon that you like, and remember the type of patch. Faint the Pokemon or capture it, but don't run. Now you must faint or capture 40 or more of the same species in a row (Poketch app #20 helps a lot with this). After you hit 40, do not run into any patches except a silver patch. The Pokeradar does Not improve your chances of finding a shiny, but merely points it out.
Tips:

DO's:

run into the farthest patch (must be one that matches)
reset the Pokeradar if you are unsure of anything

DONT's

use your bike
walk into moving grass next to walls/trees/anything that isn't touching grass on all sides
walk into moving grass that is touching another moving piece of grass
move out of view from all moving pieces of grass
take risks

Diamond Dust: This is a very rare weather effect that happens in Snowpoint City. It is just an aesthetic change meaning it is only for show. However, one of the composers of Pokemon had this put into the game on January 12th for his birthday! If you miss this, here is a picture of it:

This picture is from Bulbapedia