You evolve porygon by letting it hold the "up-grade" then you have to trade to evolve.
If you mean a polygon, as opposed to a poygon, the answer is a hexagon.
No, they are not.
You have to trade it.
level 40.
decagon
a rectangle
train it to level 40
trade it with an up-grade
you have to use a shiny stone
you have to trade it with it holdin a metal coat
It evolves at Level 30
triangle