So here's the deal. about a week ago I caught my first ever shiny. It was a ponyta (now Rapidash) Hardy nature with all around mediocre IV's (mid teens to low twenties..but nothing lower than 12). It also has Flash Fire. It was a decent find considering he could wall the fire attacks launched towards my Scizor.

Now, today while training my Lucario I ran into a shiny gastly...timid nature.

The choice should seem obvious, but here's the problem - Gastly has 20-25 in Speed IV's which is fine enough for in game (and hopefully the battle frontier). However its special attack IV's are 0-7. Should I still use him over Rapidash?

I don't really expect to compete much over wifi, the farthest I plan to go after the elite four is the battle tower and maybe a few other frontier sites. I EV train, but dont have the patience to get perfect IV's...as long as they're good enough.

If this helps, here is my team so far:

Torterra - Relaxed
Stealth Rock
Leech Seed
Giga Drain
Earthquake

Staraptor - Jolly
Fly (because I need it)
U-turn
Close Combat
Quick attack

Scizor - Adamant
Swords Dance
Pursuit
Bullet Punch
U-turn/Brick Break (undecided)

Lucario - Modest
Vacuum Wave
Aura Sphere
Dragon Pulse
Sahow Ball

Tentecruel/Vaporeon/Kingdra/Starmie (Undecided)

Slot 6 is for either Rapidash or Gengar.

Obviously the biggest problem with this team is bulky waters...which Gengar can cover with Thunderbolt..would he be strong enough to succeed though with low Special Attack?

It's between these two..dont want to breed for better IV's or another shiny gastly.

Who should I choose?