Need Help on my Dragonite

[HARlBOW]

Ive recently heard about the MultiScale+Weakness Policy Dragonite and decided to get one but the dragonite i currently have is:
Dragonite
Ability: Multiscale
Nature: Jolly
Evs:252 - Health, 252-Attack,4-speed
Ivs: 5 ivs
Moves:
Dragon Dance
Dragon Claw
Earthquake
Extreme Speed

for some reason even with multiscale i get OHKO by some pokemons like a crabominable i just faced that threw an ice punch on me and i need help if i should keep this dragonite or get a new one , im open to your suggestions.