Glaceon

Glaceon is a flawed Pokemon whose unique assets are somewhat overshadowed by its weaknesses. While STAB Ice attacks are very useful, Glaceon's limited movepool gives it few tools to abuse its huge Special Attack stat with. Glaceon's low Speed forces it to rely on its defenses, which, while decent, are largely wasted due to Glaceon's lack of resistances and multitude of weaknesses (including one from Stealth Rock).

It's not all bad news, however. Glaceon finds a niche on hail teams, where it can abuse its immensely powerful Blizzard and avoid some attacks thanks to its Snow Cloak ability. The fact that nothing is immune to Ice, together with Glaceon's lack of coverage, means that more often than not it is preferable to abuse the boosts of Choice items rather than maintain the ability to switch attacks. Overall, few teams specifically prepare for Glaceon, which may just lead to their frosty doom.