Should we add this just for completeness (even though it's implied in mephit entry)?
Summon Mephit (Sp): Once per day, a mist mephit can attempt to summon another mist mephit, much as though casting a summon monster spell, but with only a 25% chance of succes. Roll d%. On a failure, no creature answers the summons that day. A mist mephit that has just been summoned cannot use its own summon ability for 1 hour. This ability is the equivalent of a 2nd-level spell.
For ability scores, let's compare some similar mephits:
Air: Str 10, Dex 17, Con 10, Int 6, Wis 11, Cha 15, +3 nat armor
Dust: Str 10, Dex 17, Con 10, Int 6, Wis 11, Cha 15, +3 nat armor
Steam: Str 10, Dex 13, Con 10, Int 6, Wis 11, Cha 15, +4 nat armor
Water: Str 14, Dex 10, Con 13, Int 6, Wis 11, Cha 15, +5 nat armor
I'd recommend Str 10, Dex 15, Con 10, Int 6, Wis 11, Cha 15, +4 nat armor
Looking at the other mephits, it looks like most (if not all) have the following skills ranks:
Skills: Bluff +6, Escape Artist +6, Hide +6, Diplomacy +0, Disguise +0 (+2 acting), Intimidate +0, Listen +6, Move Silently +6, Spot +6, Use Rope +0 (+2 with bindings)
Feats:
Air: Dodge, Improved Initiative
Dust: Dodge, Improved Initiative
Steam: Dodge, Improved Initiative
Water: Power Attack, Toughness
I'd recommend we stick with Dodge and Improved Initiative. Or if you want to branch out, replace Imp Init with Mobility.