Clefairy
FFEF is optimal
Attack: Many damage ranges
Defence: Might be some small benefits to being lower (set up redbar on fly split), but more defence makes damage more predictable
Speed: No benefit to 15 speed fortunately, but 14 speedties boat kadabra, and outspeeds tower golbat. Can get away with 11 if willing to sacrifice these

Sandshrew
Attack: 12+ gets 62% voltorb range, 5-11 43%, lower only kills with crit, and can fail to crit ohko Raichu.
Other stats irrelevant

Dugtrio: 
Attack: with 2 x attack koga, 6 dv attack loses 10% in damage range on muk to 15 dv.
With 1 x attack koga, attack dv much more important
HP/Defence: Higher makes Koga safer, more important on 1 x attack
Special: Only relevant with 1 x attack strats, higher is better
Speed is irrelevant

Tentacool: Speed and attack are irrelevant
           Defense and HP reduce chance of dying to ponyta
           Anything less than 15 special has a damage range on Arcanine

Vulpix(35): Special: 14-15 dv has 48/66% ranges without x spec
                 10-13 dv has 25/43%

Dewgong: Speed: 15 dv ties alakazam at +1, no idea if this is relevant
         Special: Higher is better for surviving setup.

Golduck: Special: 14+ removes range on Nidoqueen, 11 has 91% range
         Speed: 12 outspeed's Nidoking at +0, always outspeed Dugtrio at +1

Ponyta: Speed: 5 dv outspeed's Jynx
        Other stats irrelevant, if Dewgong wants to kill you it will

Pinsir: Speed: 15 ties Hitmonchan at +1, 11 with a carbos, need +2 for hitmonlee anyway

Tauros: Speed is irrelevant
        Low attack+High Defense preferred to minimise confusion damage

Kingler: Speed: 9+ outspeed's Alakazam
         Defence: higher increases chance of surviving sky attack at +1 speed

Articuno: Speed: 3 outspeed's Aerodactyl at +1
          Special: 15 dv has +1% to ohko lance gyarados, +6% to ohko viridian alakazam
                   14 dv is current Articuno
                   13 dv is same as 14
                   12 dv is -1% to ohko gyarados, -5% to ohko viridian alakazam