I definitely don't think you've been in the competitive scene for long, no offense. Keep in mind there is an item clause in Subway
Jolteon: Magnet Rise seems kind of gimmicky but I won't say that it can't work
Starmie: You really won't need Rapid Spin, and I'm not sure what a fast bulky Starmie is trying to accomplish other than surviving to throw out a Rapid Spin. So I suggest Timid or Modest 252 SpA 252 Spe 4 HP Surf Psychic/Ice Beam Thunderbolt Recover/Ice Beam. Recover just doesn't seem very useful to me.
Dragonite: Unless you are using Heal Bell, Dragonite generally doesn't run Inner Focus any more. Hyper Beam is a terrible move, never use it. Based on your other moves, I would suggest Earthquake as a 4th move. And Dragonite probably needs some Speed so I would do Hasty 252 Spe 252 SpA 4 Atk for more Speed, or Mild 252 Spe 208 Spa 48 Atk for even SpA and Atk
Scizor: With Technician you use Bug Bite, not X-Scissor. I would suggest dropping the Dark move and adding Swords Dance though
Terrakion: Terrakion can run a Life Orb if you can't think of anything else. And although Retaliate is quite strong on its initial use, it really can only be used once unless you switch Terrakion back out. And a neutral Stone Edge still hits harder than a boosted Retaliate. Also consider Close Combat for this set
Mamoswine: A Jolly Ice Shard really won't hurt much, and Take Down isn't a good move. Consider using Adamant and consider Icicle Drop, Superpower, Stone Edge, and Endeavor. Toxic is kind of purposeless