Alright, couldn't get programs working in the time I was willing to spend, so I gave Seegle/Reegle/Skeegle moves and stats.
Seegle -32-> Reegle or --> Skeegle
Splash 1
Follow Me 1
Mud Slap 4
Sand Attack 5
Gust 8
Growl 12
Bubble 16
Hyper Voice 20
Bubblebeam 24
Razor Wind 28
Uproar 31
Wing Attack 33 33
Sing 35
Silver Wind 35
Glare 35
Extremespeed 39 40
Pursuit 40
Screech 43 45
Torment 45
Drill Peck 47
Sky Uppercut 50
Faint Attack 50
Psych Up 51 55
Snatch 55
Sky Attack 55 60
Crunch 60
Protect 60
Swords Dance 66
Curse 66
Flying/Water Flying Flying/Dark
HP 50 HP 100 HP 75
Attack 60 Attack 90 Attack 85
Defense 45 Defense 65 Defense 85
SAtk 40 SAtk 50 SAtk 90
SDef 45 SDef 90 SDef 85
Speed 60 Speed 95 Speed 70
Total 300 Total 490 Total 490
Fairly decent I think, but I'm out of practice so input's welcome as always. I went with loud and obnoxious plus a bit of water for Seegle, fairly hard hitting flying with some tricks for Reegle, and "chase you down, paralyze you, and eat you" for Skeegle. Stats are attack/speed heavy for Seegle (and low overall, maybe a bit too low, but it's on par with Sandshrew/Pikachu/most starters), durable attack and speed heavy for Reegle (plus extra SDef to protect a bit against electric/ice), and overall solid/average but leaning attack for Skeegle (lower health pool, higher defenses). The problem with dark-types is they rely on special attack for their damage so you have to split their attack stats if you want them to do more consistent damage, but Skeegle should work out well. One thing I wasn't sure about was evolution. I make Reegle a level evo, but I'm thinking maybe they should be stone/held item evos?