Best pokemon to beat a dragonite

Ditto can be good, as it uses the move Transform. But you wanna try for Ice, Rock, Dragon and Fairy.

Lapras

Ditto

Golduck

dragonite

Zapdos

Lapras

Better use Ice ,Fairy or Dark Type.

Gyarados with dragon breath. Unfortunately, you can't evolve magicarp to this moveset anymore. I have one, and it kicks any Dragonite. Wigglytuff is also good against Dragonite.

Dewgong and cloyster won't ever take super effective DMG from any of dragonites moves due to being ice and having water canceling steel wings steel type. You wanna try for blizzard as ya it best bet for dmg but it seems your quick attack is more preferential than essential. Don't forget always go ice on dragonite there's no way around that 4X dmg from ice to dragon. I can also use fairy moves/Pokemon but I find they are harder to get ahold of for some, their move pools feel too big or random and they tend to be more tanks which I don't really wanna be when trying to counter a top tier Pokemon that can still hit u back with steel wing for 2X dmg. (Thanks to trainer tips on YouTube for teaching me the basics of all this info) PS lapras is nice but cloister is easier to get and cloyster has nearly 3X the defense over lapras whereas lapras makes up for that loss with having just over 2X the stamina(health) good luck and good hunting