Blissey's moveset is illegal in Competitive battling because of Double Team, you can go for Counter to do massive damage on pokemon like T-Tar and other physical powerhouses.
Mienshao has no need for 2 Fighting type attacks so a good choice here would be Stone Edge, as Starke said in the comment.
Milotic has no reason to hold the Water Gem except power, which you'll prefer reliability over, so give it Leftovers and either Toxic instead of Hydro Pump or Scald instead of Surf, because the two together wouldn't be as effective.
Gengar's Focus Band is banned from competitive battling, so a better choice would be Life Orb for raw power.
Scizor's moveset is just fine, so nothing to talk about.
Gliscor's moveset is really good! But I would give it Dragon Tail because then you can manipulate the foe into the pokemon you want.
Overall - you did a great job putting this team! Good job!