The team is just for battle spot doubles
Mamoswine: 252 Speed, 252 Atk, 4 Hp. Nature: Jolly
Hitmontop: 252 Speed, 252 Def, 4 Hp. Nature: Jolly
Kangaskhan: 252 Speed, 252 Atk, 4 Hp. Nature: Jolly
Lapras: Hp 252, SpD 253, 4 SpA. Nature: Calm
Aegislash: 252 Def, 252 SpD, 4 Atk. Nature: Sassy
Heatran: 252 SpA, 252 Speed, 4 Def. Nature: Naive
Mamoswine doesn't need Rock Slide since its STABs have good coverage on their own:
-Icicle Crash/Icicle Spear
-Earthquake
-Ice Shard
-Protect
Nature: Jolly/Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb/Focus Sash
Ability: Thick Fat
Lapras' defensive typing is terrible. Better bulky Water Pokemon to turn to are Araquanid or Gastrodon, the former of which can provide Wide Guard support and fire off powerful Liquidations, and the latter which can act as a handy counter to opposing Water Pokemon with Storm Drain:
Araquanid:
-Liquidation
-Lunge/Leech Life/Toxic
-Wide Guard
-Protect
Nature: Adamant/Brave
EVs: 252 HP/252 Atk/4 SDef
Item: Waterium Z/Mystic Water/Splash Plate
Ability: Water Bubble
Gastrodon:
-Scald
-Toxic
-Ice Beam/Sludge Bomb/Clear Smog/Earth Power/Recover
-Protect/Recover
Nature: Sassy
EVs: 204 HP/116 Def/188 SDef
Item: Sitrus Berry/Aguav Berry
Ability: Storm Drain
Kangaskhan currently lacks a powerful attack in general. Sucker Punch is unreliable as it relies on the opponent about to use an offensive move; that move needs good prediction:
-Fake Out
-Return/Double-Edge
-Power-up Punch/Low Kick
-Sucker Punch
Nature: Jolly/Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Kangaskhanite
Ability: Scrappy
Aegislash needs stronger STAB moves to function; just having Shadow Sneak alone isn't going to cut it. You're also EVing it the wrong way, as when Aegislash switches forms, it doesn't carry over its EVs from its defenses to its offenses:
-Shadow Ball
-Flash Cannon/Sacred Sword
-Wide Guard/Substitute
-King's Shield
Nature: Quiet
EVs: 252 HP/252 SAtk/4 SDef
Item: Leftovers/Weakness Policy
or
-Flash Cannon
-Shadow Ball
-Sacred Sword/Shadow Sneak
-King's Shield
Nature: Quiet
EVs: 252 HP/4 Atk/252 SAtk
Item: Life Orb/Spooky Plate/Spell Tag/Weakness Policy/Ghostium Z
While Heatran can go fast in doubles, its Speed isn't good enough for that to happen unless you're providing Tailwind support. A Naive nature is pointless when Heatran isn't using physical attacks:
-Heat Wave
-Flash Cannon
-Earth Power/Substitute
-Protect
Nature: Modest
EVs: 180 HP/252 SAtk/76 Spe
Item: Shuca Berry/Leftovers
Hitmontop is better relegated to a bulky support role since any offensive role it can do its outclassed by other Fighting Pokemon like Breloom:
-Fake Out
-Close Combat
-Wide Guard
-Helping Hand/Quick Guard/Feint
Nature: Adamant
EVs: 252 HP/252 Atk/4 Def
Item: Sitrus Berry/Lum Berry
Ability: Intimidate
However, Arcanine is capable of compressing Heatran's and Hitmontop's roles as a bulky Fire Pokemon that provides Intimidate support:
-Flamethrower
-Snarl
-Will-o-Wisp
-Protect
Nature: Timid
EVs: 148 HP/4 Def/164 SAtk/28 SDef/164 Spe
Item: Sitrus Berry
Ability: Intimidate
or
-Flare Blitz
-Wild Charge
-Crunch/Extreme Speed/Snarl
-Protect
Nature: Adamant/Jolly
EV: 28 HP/180 Atk/4 Def/44 SDef/252 Spe
Item: Life Orb/Mago Berry
Ability: Intimidate