highest DPS by type- Starmie

because starmie have better attack stat compare to vaporeon

Starmie atk stat : 210
vaporeon atk stat : 205.

eventhough not too much but still higher :)

It only takes their attack stat into consideration, which means that while Starmie will hit a little bit harder, Vaporeon will last significantly longer and therefore doing more damage in the end. That section is only measuring damage per second, which in itself is a really poor way of comparing different Pokémon. Don't worry about it too much, when the attacker tier list is out you will see Vaporeon probably in tier 1 - 1.5 while Starmie is nowhere to be seen.

Starmie's base attack stat is slightly higher than Vaporeon's, so will do slightly more damage with each use of the same water move. These rankings aren't the whole story however, because Vape has way more HP. So it depends on the balance between using the quick and charge move, and that in turn depends a bit on whether you need (or want) to dodge or can just stand and fight. That in turn depends on how powerful your enemy is. If your enemy is so strong that you need to dodge with your (much lower HP) Starmie, then time lost while dodging means less DPS in practice. Moreover, because your charge move charges both through using your fast move and taking damage, you can't use it as often if your are dodging. Vape has enough health to just stand and fight against most enemies (perhaps just dodging their charge moves), and the damage you take charges Hydro pump or aqua tail super fast. So in most real world fights Vaporeon will have the higher DPS.