Help with my NU team

[RaisinBran]

I feel like some of my team members don't have good synergy with the rest of the team (mainly Torterra), any suggestions would be much appreciated

Kangaskhan @ Leftovers
Ability: Scrappy
EVs: 4 HP/ 252 Atk/ 252 Spe
Adamant Nature
- Return
- Drain Punch
- Earthquake
- Wish

Torterra @ Leftovers
Ability: Overgrow
EVs: 252 HP/ 252 Atk/ 4 Def
Adamant Nature
- Earthquake
- Wood Hammer
- Stealth Rock
- Synthesis

Rapidash @ Life Orb
Ability: Flash Fire
EVs: 252 Atk/ 252 Spe/ 4 Def
Adamant Nature
- Flare Blitz
- Wild Charge
- Drill Run
- Morning Sun

Walrein @ Choice Scarf
Ability: Thick Fat
EVs: 252 SpA/ 252 Spe/ 4 HP
Modest Nature
- Ice Beam
- Surf
- Hidden Power Electric
- Signal Beam

Claydol @ Leftovers
Ability: Levitate
EVs: 252 SpA/ 252 Spe/ 4 HP
Modest Nature
- Earth Power
- Psychic
- Rapid Spin
- Stealth Rock

Hariyama @ Choice Scarf
Ability: Sheer Force
EVs: 252 Atk/ 252 Spe/ 4 HP
Jolly Nature
- Close Combat
- Knock Off
- Earthquake
- Thunder Punch

 

[Khaotic Kebab]

All of your Pokemon are just focused on offense at the minute. In Torterra, Claydol and Hariyama especially, you'll probably need to be more focused on defense. Though I hate it, Smogon does have some good template EV spreads upon which you can base your's, so check them out.

 

[PlatinumDude]

A Jolly nature is better for Rapidash as without it, it gets outsped by base 100s. 105 Speed is a good Speed tier in NU, so might as well take advantage of that.

Walrein isn't a really good offensive Pokemon, really, because of its bad defensive typing and low Speed. Better offensive Water Pokemon to turn to are Barbaracle (sure, it has a bad defensive typing too, but Shell Smash fixes its low Speed), Floatzel, Frogadier (both sport high Speed), Samurott (decent bulk) and even Lanturn (while its offensive presence is average at best, it makes a pretty good pivot):

Barbaracle:
-Stealth Rock
-Stone Edge
-Grass Knot/Endeavor
-Taunt
Nature: Naive/Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Focus Sash
Ability: Tough Claws

or
-Shell Smash
-Razor Shell
-Stone Edge
-Cross Chop/Grass Knot
Nature: Jolly/Naive
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb/Lum Berry/White Herb
Ability: Tough Claws

Floatzel:
-Waterfall
-Ice Punch
-Return
-Switcheroo/Aqua Jet/Brick Break
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Band
Ability: Water Veil

Frogadier:
-Hydro Pump
-Gunk Shot
-Ice Beam
-Grass Knot/U-turn/Hidden Power (Fire)
Nature: Naive
EVs: 252 Atk/16 SAtk/240 Spe
Item: Life Orb
Ability: Protean

Lanturn:
-Scald
-Volt Switch
-Heal Bell
-Protect/Thunder Wave/Ice Beam
Nature: Calm
EVs: 40 HP/232 Def/208 SDef/28 Spe
Item: Leftovers
Ability: Volt Absorb

or
-Hydro Pump/Scald
-Volt Switch
-Ice Beam
-Hidden Power (Fire)/Thunderbolt
Nature: Modest
EVs: 252 SAtk/204 SDef/52 Spe
Item: Assault Vest/Leftovers
Ability: Volt Absorb

or
-Hydro Pump/Scald
-Volt Switch
-Signal Beam/Ice Beam
-Thunderbolt/Hidden Power (Ground/Fire)
Nature: Modest
EVs: 252 SAtk/72 SDef/184 Spe
Item: Choice Specs
Ability: Volt Absorb

Samurott:
-Hydro Pump
-Ice Beam
-Grass Knot
-Knock Off/Superpower/Aqua Jet/Taunt
Nature: Rash/Modest
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb
Ability: Torrent

or
-Swords Dance
-Waterfall
-Megahorn
-Aqua Jet
Nature: Adamant
EVs: 120 HP/252 Atk/136 Spe
Item: Life Orb/Lum Berry
Ability: Torrent

Torterra already provides Stealth Rock for the team, so it isn't really needed on Claydol, IMO:
-Earth Power
-Psychic/Psyshock
-Shadow Ball
-Rapid Spin
Nature: Modest
EVs: 4 HP/252 SAtk/252 Spe
Item: Leftovers/Soft Sand/Earth Plate

Not even a Choice Scarf can save Hariyama's bad Speed, as it doesn't boost it enough to outspeed things. Hariyama should still focus on its bulk. To put things in perspective Timid/Jolly base 100 Speed Pokemon still outspeed Choice Scarf Hariyama:
-Close Combat
-Knock Off
-Bullet Punch
-Earthquake/Fake Out
Nature: Adamant
EVs: 252 Atk/4 Def/252 SDef
Item: Assault Vest
Ability: Thick Fat/Guts

or
-Close Combat
-Knock Off
-Earthquake/Facade
-Bullet Punch
Nature: Adamant
EVs: 252 Atk/116 Def/140 Spe
Item: Choice Band
Ability: Guts