TLDR; Piloswine is irrelevant to the meta. Stick with Cloyster
There seems to be some confusion on how to counter Dragonite. Tripledex recommends Piloswine and Dragonite. But the answer is Cloyster. Here’s why.
Piloswine’s moves get really high DPS. Powder Snow has one of the highest EPS, so it boosts Avalanche like crazy. Plus, Piloswine has good stamina, so theoretically you can send multiple Dragonites to the Ice Age. But there are holes to this logic.
The problem is that Piloswine has terrible defense base stats. So Dragonite is going to rip through all your stamina, and Piloswine is going to end up drinking all your pots.
The other problem is that Powder Snow has terrible DPS. So this detracts from the EPS boost to Avalanche.
Cloyster’s Frost Breath has good DPS. Moveset-wise, the benefits of Frost Breath’s DPS and Powder Snow’s EPS are about equal.
Cloyster’s high Defense stat is the right answer to Dragonite’s high Attack stat. So Cloyster comes out way ahead in the damage exchange.
Granted, Cloyster has low HP. Just learn how to dodge and you’ll be fine.
As for using Dragonite to counter Dragonite, this is a pretty bad idea. You’re missing out on that rare 1.5x stacked type effectiveness. And you’re just as vulnerable, so you basically have no advantage.
Note: There are some merits to using Dragonite to counter Dragonite. Yes, you have zero type and stat advantage. But zero is actually a decent number, since Dragonite with DT/O is the best in the game.
Cloyster is basically the only one mon with a significant advantage against Dragonite.