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