never evolve pokemon as soon as they hatch
you gotta put this into perspective
youre a magical monster and you suffer severe physical changes as soon as youre born
heres the trick
study the evolution movepool
find a certain move that is relevant to the pokemon
like when charmander learns flamethrower, thats when you evolve it
for a staryu
i reccommend level 42, when it learns psychic
or level 53 when it learns hydro pump
try evolving them when they learn their moves by themselves , not through tms or tutors
picture it as
staryu´s psychic abilitys have become so strong
its ready to evolve into starmie
also, this
https://www.youtube.com/watch?v=9p6DSVyyT8k 
