pokemon-series
There's a pokemon I think should evolve, so I'm making my own fake one, and I'm doing everything about it, like base stats and move pool and all.
So what I want to know is how much does each base stat change after a pokemon evolves.
For example, Bulbasaur has base stats of 45 49 49 65 65 45. Ivysaur's base stats are 60 62 63 80 80 60 and the differnces are 15 14 15 15 15 15. What I want to know is the average change across all Pokemon using this method of calculation.
The stats for a Pokémon are based on:
The relevant formulas are:
and
for the first and second generation, and:
and
for the third and fourth generation.
As you can see, nowhere is there any mention of having a gym badge in these formulas.
The theory as to why the game tells you there is a stat boost that, in my opinion, holds the most ground, is that the EVs you get from battling the gym leader's Pokémon match the stat that they tell you gets raised.
Yes, a shiny pokemon will remain shiny after evolution.
Upon evolution, a Pokémon will retain its Shiny status. A Shiny Charmander, if leveled up, will eventually become a Shiny Charmeleon and then a Shiny Charizard, just as a regular Charmander will become a regular Charmeleon and then a regular Charizard. This is due to the status being determined by values inherent to the Pokémon.
Best Answer
I gathered the information on pokemon stats and evolution lines from bulbapedia (Up to gen VI, or #721), and threw it all into a spreadsheet to do some calculations.
Here is the relevant table of stat changes when evolving. Results are rounded to nearest integer.
Note that your desired values for all evolutions are
Mega evolutions were not included, and they will always increase the base stat total by 100 (but individual stats could decrease).
As a side note, a new (non-mega) evolution should probably have no more than 600 total stats, as this is the value for "pseudo-legendaries", which are the typical peak for non-legendary pokemon.
Sources:
1 - Pokemon Stats
2 - Evolution Lines
3 - Pseudo-Legendaries