Move Charizard's last 4 EVs into Defense so that it doesn't die to 2 Stealth Rock switch-ins while in base form.
Suicune, Gastrodon, Tentacruel, Slowking, Starmie, Alomomola and Vaporeon are lower-tiered Water Pokemon with OU relevance, so they're better options over Lapras. Lapras isn't that good, really; its defensive typing is terrible, and there are better Pokemon who do its roles better:
Suicune:
-Calm Mind
-Scald
-Rest
-Sleep Talk
Nature: Bold
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Gastrodon:
-Scald
-Earth Power/Ice Beam/Earthquake
-Toxic
-Recover
Nature: Bold/Relaxed
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Ability: Storm Drain
Tentacruel:
-Scald
-Acid Spray
-Sludge Bomb/Knock Off
-Rapid Spin
Nature: Bold
EVs: 252 HP/224 Def/32 Spe
Item: Black Sludge
Ability: Liquid Ooze
Slowking:
-Scald
-Psychic/Dragon Tail
-Fire Blast
-Power Gem/Ice Beam
Nature: Calm/Sassy
EVs: 248 HP/164 SAtk/96 SDef
Item: Assault Vest
Ability: Regenerator
or
-Scald
-Psyshock
-Thunder Wave
-Slack Off
Nature: Calm
EVs: 248 HP/44 Def/216 SDef
Item: Leftovers
Ability: Regenerator
Starmie:
-Hydro Pump
-Psyshock/Thunderbolt
-Ice Beam
-Rapid Spin
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Leftovers
Ability: Natural Cure/Analytic
or
-Scald
-Reflect Type
-Rapid Spin
-Recover
Nature: Timid
EVs: 248 HP/20 Def/16 SDef/224 Spe
Item: Leftovers
Ability: Natural Cure
Alomomola:
-Wish
-Protect/Magic Coat
-Scald
-Toxic
Nature: Calm
EVs: 36 HP/220 Def/252 SDef
Item: Leftovers/Rocky Helmet
Ability: Regenerator
Vaporeon:
-Wish
-Protect
-Scald
-Ice Beam/Toxic/Heal Bell
Nature: Bold
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Water Absorb
Amoonguss outclasses Vileplume by a long shot. Like the Pokemon above it, it's a lower-tier Pokemon that sees OU use. Amoonguss has Regenerator for passive recovery upon leaving battle, as well as a more reliable sleep move in Spore. Really, what does Vileplume do that Amoonguss can't?:
-Spore
-Giga Drain
-Foul Play/Hidden Power (Fire)
-Sludge Bomb/Clear Smog
Nature: Bold
EVs: 252 HP/136 Def/120 SDef
Item: Black Sludge
Ability: Regenerator
Rhyperior is a better option over Eviolite Rhydon simply because Solid Rock helps cushion its common weaknesses, plus it hits just a bit harder, and that could make a big difference. Also, all three of Rhydon's abilities are all useless on it. Rhyperior's ability to hold Leftovers also outweigh's Rhydon's Eviolite-boosted bulk; Rhydon can get worn down easily without reliable recovery or Wish support:
-Stealth Rock
-Earthquake
-Stone Edge/Rock Blast
-Ice Punch/Megahorn/Toxic
Nature: Adamant
EVs: 212 HP/44 Atk/252 Def
Item: Leftovers
Ability: Solid Rock