Okay, so the levelling of characters on this forum is not the levelling of your trainer themselves, rather the training up of the various pokemon that travel with them. In conjunction with the latest games; Diamond, Pearl and Platinum; pokemon will have a minimum level of 1, and a maximum of 100.
Below is listed the various amounts of experience that your pokemon require in order to rise up through the levels, as well as how many stat points you get to distribute between the various stat areas each time they level up. With this customisable feature on the forum it means that your pokemon can be completely custom; though it is advisable to attempt to keep the stats even, rather than incredibly unbalanced and the only rule is that no more than 100 points can be added to any single stat.
Levels 1-10: 30EXP per level, 2 stat points per level.
Levels 11-20: 60EXP per level, 2 stat points per level.
Levels 21-30: 90EXP per level, 2 stat points per level.
Levels 31-40: 100EXP per level, 3 stat points per level.
Levels 41-50: 125EXP per level, 3 stat points per level.
Levels 51-60: 150EXP per level, 3 stat points per level.
Levels 61-70: 175EXP per level, 3 stat points per level.
Levels 71-80: 200EXP per level, 2 stat points per level.
Levels 81-90: 250EXP per level, 2 stat points per level.
Levels 91-100: 350EXP per level, 2 stat points per level.
Now this presents a problem, yes pokemon can be customised , but they can also be totally unrealistic. A good example of this would be a Steelix with massive special attack, but no Defence (when in reality, we all know a Steelix would be prided on its Defensive prowess) so, to make this so, we here at pokemon Hunters use the Base-Stat system given to us by the game itself! Each and every pokemon from Pidgey to Porygon2 has it's own unique stats that make it what it is: a lot like DNA. This is why a Charizard is significantly stronger than a Weedle. These Base stats determine your pokemon's stats here on the forum. Take Bulbasaur as an example:

Image copyright BulbapediaThese are a Bulbasaur's base stats and they show how good it is at particular things. Now using our system, we say that these nubmers here are how good a pokemon is at maximum (level 100) so, to work out it's stats at a certain level, find out a percentage of the stats equal to the level. Taking the same Bulbasaur as an example, at level 5 he would be at 5% (1/20 if your into fractions) of his total power so we take the base stats and times them by 1/20 to get:
HP: 2.25
Attack: 2.45
Defense: 2.45
Special Attack: 3.25
Special Defense: 3.25
Speed: 2.25
Yes there's decimals but these are rounded to the nearest whole number. So on out forum, a starter level 5 Bulbasaur would have stats of:
HP: 2
Attack: 2
Defense: 2
Special Attack: 3
Special Defense: 3
Speed: 2
Which healthily reflect its overall base stats.
Now, when you level up you can use the stats points you gain to add to these numbers and make them stronger. This way, it reflects the EV system from pokemon games (but if you don't know what that means then don't worry, it's not important).
Any questions on how to calculate your stats, do not hesitate to PM a member of staff (especially Chazz as he came up with the maths of the System).[/size]