Dots is what we call a pokemon's predilection towards certain stats. Like a Geodude's defense, or a Scyther's speed. Every pokemon has between 1 and 5 dots in their stats, 1 meaning poor, 2 meaning fair, 3 being average, 4 being good, 5 being great. For instance, a shuckle's defense and special defense would both be 5, meaning great, but every other stat would be 1 meaning poor. These dots are provided to the moderators from a few sources, and are not made up.
The more dots a pokemon has in a stat, the cheaper it is to upgrade it via exp.
1 dot gives a =0% discount
2 gives a 10% rounded down
3 gives a 20% rounded down
4 gives a 30% rounded down
5 gives a 40% rounded down
The discount applies everytime you use exp to upgrade.