HP IV: 17 [13 ~ 22] 9%
Attack IV: 5 [1 ~ 10] 6%
Defense IV: 29 [27 ~ 31] 23%
Sp.Atk IV: 10 [6 ~ 15] 7%
Sp.Def IV: 29 [27 ~ 31] 23%
Speed IV: 23 [19 ~ 28] 9%

It's modest by nature, so has increased SP ATK (at the cost of normal attack), but still the SP ATK IV is kinda low.. Its fast and good defended though..

Since Starmie is one of the fastest pokemon out there anyway i was thinking giving it cyroball, psychic, a special water attack and recover.

Anyway, this is more about the IV. Should I go with this?

Also, I was thinking for EVs: 255 SP ATK, 155 SP, 100 SP DEF (or HP).