And the best lapras counter goes to...
Answers
If I can recall correctly, Dragonite used to be the best Lapras counter back in the days, despite his type disadvantage.
This was before the type advantage update. Anyway, I'm sure it's still a viable choice to put in some damage. However, I'm not sure if this still holds against a raid boss who can kill a Dragonite in a single shot.
Also pretty sure the player who fought the Lapras didn't over think all of above.
I'd be interested to see what comes up in a water lapras 'autoselect'- it may actually include dragonite but the game seems to favour typing selection over DPS selection.
Then again the chances of a water lapras is 1/6. 1/3 if you just count hydro pump. Most people bet that the pokemon doesn't have a moveset (e.g. betting on Lugia not to have HP or Mewtwo doesn't hv FB and use Ttar), rather than betting the boss has one specific moveset.