There are a lot of Pokemon that can be considered cute in the franchise, from Legendary and Mythicals all the way down to the babies.
Baby Pokemon are typically the cutest, but they are also the weakest. They have a long way to go in order to evolve and reach their potential. Those evolutions often aren't as cute.
Near the top of the strength list sits some hideous Pokemon such as Slaking and the terrifying Eternatus. Thankfully, they are joined by some of the cuter, more powerful creatures in the series.
Note: This article is subjective and reflects the opinion of the writer.
Top 5 cute but strong Pokemon
#5 - Tsareena
Tsareena has a base stat total of 510. That matches the likes of Braviary, Poliwrath, and Steelix. Known as the Fruit Pokemon, Tsareena is a cute mangosteen with legs. It maintains the cuteness found in Bounsweet all the way to this final evolution. With a 120 base attack state, Tsareena is pretty dang strong.
#4 - Roserade
Roserade is cute in the same way that Tsareena is. The Bouquet Pokemon is absolutely gorgeous in terms of design. It also maintains its cuteness from its beginning days as a Budew. 515 is its base stat total, matching those such as Aerodactyl and Gigalith. Its strength comes in the form of great Special Defense and Special Attack.
#3 - Celebi
Celebi is one of the cutest Mythical Pokemon around. It has a base stat total of 600. All six of its stats are equal at 100 a piece. There are quite a few non-Legendary and non-Mythical with that total. Alakazam, Houndoom, and Scizor are a few that come to mind. Celebi is known as the Time Travel Pokemon. While it may be a small fairy-like creature, it is very powerful.
#2 - Diancie
Like many Mythical Pokemon, Diancie falls in the cute category. It has a 600 base stat total like Celebi, but Diancie also has a Mega Evolution. That boosts the total up to 700. Both defensive stats are an even 150 while both attack stats are an even 100. The Jewel Pokemon is super cute.
#1 - Mew
The strongest, cutest Pokemon is none other than Mew. This Mythical maintains a 600 base stats total trend like the last few entries. Like Celebi, each stat is a solid 100. Mew is said to have the DNA of every single Pokemon in its body. That gives it access to every attack. That is pure strength matched with utter cuteness right there.