Seeing how Steel-types can be a bitch to this team, I would consider adding mons like Garchomp, Zapdos, or Gastrodon over Gardevoir's slot. Garchomp and Gastrodon can both utilize Ground STABs to remove Steel-types, while Zapdos has Heat Wave. Gastrodon provides you another Pokemon to check Rain, so you can be more flexible with your teammates, rather than always tacking on Abomasnow when facing Rain teams. Garchomp can be useful when facing Sand teams. Zapdos can provide this team with another Tailwind support (although you may want to utilize 3 atks instead).
I think I will stick with Life Orb on Infernape and go with Rock Gem on Rampardos. You should test it out, though, and see which item fits better.
Since you lack Rain now, I would consider dropping Thunder for Thunderbolt or Substitute on your Gengar. I also highly recommend going Timid on Gengar, cuz it's a frail mon that depends heavily on its Speed to finish off the opponent before they can attack.