Keep the Base Stats in one column on the Pokemon’s character sheet. Keep the added stats, gained through level up, in another column. Keep their Actual Stats in the third column. The Actual Stats is the sum of the Base Stats and added stats.
Here is a neutral Nature Charmander’s Base Stats. This Charmander is at level 1.
HP - 4
ATK - 5
DEF - 4
SPATK - 6
SPDEF - 5
SPEED - 7
When a Pokemon levels up, you must put one stat point into a stat that won’t ruin the Base Relation of a Pokemon’s base stats. The Base Relation of stats is the order of the stats according to the highest Base Stat of a Pokemon, followed by the seconded highest Base Stat and the next highest Base Stats after that, until you have created a list of the order of a Pokemon’s Base Stats from highest to lowest. Ruining the Base Relation means when you add a Stat Point to a stat while leveling up, the Base Relation was changed.
This Charmander’s Base Relation is:
Speed (7) > Special Attack (6) > Attack and Special Defense (5) > Hit Points and Defense (4)
This means you must put a stat point into Charmander’s SPEED at level 2. So that the Special Attack of the Charmander does not equal Speed, ruining the Base Relation.
When it comes to ties in a Pokemon’s Base Relation, you never need to keep those two stats equal. The difference between two stats, tied in the Base Relation, does not matter, as long as the next highest stats in the Base Relation is kept higher then the tied Base Stats and the next lowest stats in the Base Relation is kept lower then the tied Base Stats.
Let’s say at level 4, you added to Charmander’s ATK. This is what its stats now look like:
In order to preserve Base Relation, at level 2, 1 point was added to SPEED. At level 3, 1 point was added to SPATK. At level 4, 1 point was added to ATK. At level 5, for example, you may not add to HP or DEF because that will ruin Base Relation. It would tie with ATK.
Here is that Charmander at level 20, when spreading its stats evenly.
Notice that the Stat points that are being added are almost all equal per different Stat when choosing to evenly distribute Stats.
Here is that same Charmander when its trainer is raising its prominent stats.
The Base Relation of the Base Stats is maintained here. You do not need to add stats evenly as long as the Base Stats’ Base Relation is kept.
Here is that same Charmander when its trainer is trying to make it hit harder with Melee Moves.
This can be frustrating when you want a Charmander who is a Melee sweeper. This is where Natures come in to play.
A Brave, which adds ATK and takes SPEED, natured Charmander instead would have these base stats:
HP - 4
ATK - 7 (Instead of 5)
DEF - 4
SPATK - 6
SPDEF - 5
SPEED - 5 (Instead of 7)
A Nature will add two to a Base Stat and subtract two to another Base Stat, making a completely different Base Relation in many cases. Now you can focus more on this Charmander’s ATK without even worrying about increasing its SPEED.
IMPORTANT: The only exception is the HP stat! When a Nature adds to or takes from the Base Stats in the HP category, the HP Base Stat is only changed by 1 point.
Look at this Brave Charmander, now at level 20.
This Charmander can now potentially be a sweeper with its superior ATK and SP.ATK, plus with some SPEED it gains evasion bonuses. Though, due to its lower other stats, if this Charmander fails to defeat an opponent it is likely to be swept itself.
Like Natures, Vitamins can alter Base Stats. Vitamins are expensive items that can be fed to a Pokemon, with any combination of 5 vitamins at max, improving a Pokemon’s Base Stats in order to allow them to change how they distribute stats as they level up.
A Base Stat can never be 0 as a result of Nature. If a Pokemon’s Nature changes a Base Stat to 0, instead the stat is 1.
Starting at level 51, Pokemon gain two Added Stats per level gained. These two stats may not be put into the same Stat. When adding stats, a Pokemon’s Base Relation must still be maintained.
Starting at level 76, Pokemon gain three Added Stats per level gained. These three stats may not be put into the same Stat. When adding stats, a Pokemon’s Base Relation must still be maintained.
On the Natures page is a chart of Natures and how they effect your Pokemon’s Base Stats.
Natures also effect what kinds of food your Pokemon like.