Stat change after evolving?

Question

When a pokemon evolves their stats increase, but what affects the change?, what determines how much it increases?

Answer 1

This is the formula to calculate a pokemon's Stats except HP.

The IV, EVs, and nature would stay constant if the pokemon evolves (not including the ones it would gain if it levels up, but this is just for the sake of simplicity.) The base stat would change upon evolving though. Since this changes, the pokemon's stats will as well. Most of the time it is an increase, which is why your pokemon's stats usually jump up more than usual when they evolve.

Answer 2

their base stats. there's little charts on all the pokemon pages on this site, so you can look up say, gastly and then look up haunter and you'll have a good chart to look at on how much better the stats would get upon evolving