Whether it is due to false expectations or disappointment at the end result, not all Pokemon evolutions have been popular with the fanbase.
In most cases, this isn't even due to usability, such as stats or abilities. A Pokemon's reception (or lack thereof) is often due to its appearance, its pre-evolution(s), or Pokemon similar to it in one way or another.
So if a Pokemon is on this list, it's not necessarily because it's bad or hated. It's simply because it wasn't well-received.
Note: This article is subjective and reflects the opinion of the writer.
Top 5 Pokemon evolutions that players did not like
#5 - Dubwool
Dubwool is one of many Pokemon whose lack of popularity stems not from being a bad evolution, per se, but because its pre-evolution was so incredibly loved and well-received.
Wooloo is, by far, one of the most popular Normal-type Pokemon, with popular Twitch streamer and YouTuber RTGame spending many hours farming for a shiny Wooloo before even beating the first gym. He then proceeded to beat the entirety of Pokemon Shield with said shiny Wooloo, which he had lovingly named Cupcake.
The point of all of this is that compared to the beloved popularity of Wooloo, Dubwool just didn't live up to its smaller, fluffier form's hype.
#4 - Chesnaught
Chesnaught appears to have inherited all of the ill-will that previous Fighting-type starters received in generations past.
Its stats are fairly decent, both of its abilities are usable and its move pool sports some good coverage. However, due to the popularity of Generation VI's other two starters and/or its bulky design, Chesnaught was the least popular of the Kalos region's three starters among fans of the Pokemon franchise. It may even be one of the least popular starters to date.
#3 - Emboar
Emboar is a poor soul who fell prey to the unfortunate circumstances of being the third Fire and Fighting-type starter in a row. The Fire/Fighting boar Pokemon has a fantastic design, and while it's outclassed by a few other Pokemon, it still possesses acceptable stats and super-powerful moves.
However, not only was it the third of the FIre/Fighting starter Pokemon, but it was also the least well-received. Blaziken is a classic fan-favorite, and Infernape garnered a solid amount of devoted fans as well. With competition like that, it's no wonder that Emboar received the brunt of the fanbase's disdain concerning Nintendo's starter-type choices.
#2 - Alolan Persian
When an Alolan variant of Meowth was revealed, fans were fairly excited for the new take on the old favorite. And while Persian had always fallen short of Meowth on the popularity front, many fans believed that this was a chance for Persian to pull in some popularity of its own.
To put it lightly, those fans were sorely disappointed. While Alolan Persian did get quite the boost in terms of usability, it still wasn't the best, and it looked like this. Compared to the sleek and dignified design of Persian, the new, softer look did not work well.
#1 - Lickilicky
There was a resounding chorus of gratified cries as Generation IV gave many Pokemon some much-needed love in the form of new evolutions. Electabuzz with Elctivire, Magneton with Magnezone, and Togetic with Togekiss are a few of them, all getting some fantastic new stats and moves to accompany their new impressive forms.
And then there's Lickitung with Lickilicky.
Lickilicky got better stats, sure. But it was difficult to optimize back when it came out and has only gotten worse as Pokemon that can outclass it have been released.
While Lickitung has a funny design, being roughly half tongue with some blank and soulless eyes, Lickilicky looks more like a failed Majin Bu clone that advertises free WiFi rather than a Lickitung evolution.
Having said that, Lickilicky is one of the very few Pokemon that can learn Explosion and use it with STAB (Same Type Attack Bonus), so it definitely has its good sides. However, in terms of how it is as an evolution, it wasn't well-received at all.