1.Stats: Should Starmie get a stat boost, Evolution, Mega Evolution or nothing?
Starmie has 520 BST, which can be increased by +5 BST to match Cloyster. Or it can be increased at maximum of +20 BST.
An evolution would be nonsensical. A side evolution, mid-evo, or a pre-evo for Staryu would make more sense.
A Mega would be cool.
2.Should Starmie get more abilities?
Probably. Illuminate is a useless Ability, so it can be replaced by something better. Analytic is also incredibly unfitting for Starmie's Speed. Regenerator, Protean or Magic Bounce would make more sense.
3. Should Starmie get more moves?
Yes. Water Shuriken is an obvious idea, but outside of that Nasty Plot would be a fine option.
4.What additional typing Starmie can have?
Ice, Electric, Rock are the obvious options. Normal and Ghost are potential options.