Class changing problem and percent stat change

[Æ№∞₧]

I want to make a game where you can change your class at let's say level 10, but the level cap is 20.
How do I make it so that you can change class at level 10, but you are stronger if you change class at level 20?
Also, how do I make it so that a character has a chance (like 20%) to increase in a skill at level up?

 

[Cryranos]

If you're using XP, i believe either Trickster or Sephiroth Spawn wrote a random curve generator.

If this is for your Fire Emblem thingy, that would mimic the RNG-based leveling stat gains, thus a 10/20 character will be weaker than a 20/20 character. However, you'll have another problem when you return the level to 1.

 

[Æ№∞₧]

However, you'll have another problem when you return the level to 1.

Exactly!

 

[Cryranos]

You could save all of the stats as variables, then add them to the basic stats of the new class, instead of what fire emblem does, adding the basic stats of the new class to the current stats.