Some of the most powerful Pokemon are Ground-type, but quite a few could be considered underwhelming. Underwhelming does not necessarily mean they are disliked. It simply means they don't make an impact, as a Pokemon in general or in battle like the others do.
The Ground-type category is pretty diverse when it comes to its creature and dual typings. Some don't work and don't do the type category justice.
Note: This article is subjective and the opinion of the writer.
5 most underwhelming Ground Pokemon of all time
#5 - Rhyhorn
Rhyhorn just doesn't cut it when it comes to Ground-type Pokemon. For most players, the only reason to catch a Rhyhorn is to evolve it into a Rhyperior eventually.
#4 - Galarian Stunfisk
The Galarian form of Stunfisk is quite underwhelming. As a Ground/Electric-type, it has a unique type combination. This form is Ground/Steel, however.
That simply adds to its weaknesses. The Galarian Stunfisk does get a lot of love, but it isn't a Pokemon to pine over. Also, it's just bizarre.
#3 - Camerupt
Camerupt is a Fire/Ground-type Pokemon. That gives it an absolutely insane weakness to Water-type attacks. It is a cool volcanic camel, but that's all it has going for it.
There are much better Fire-types and much better Ground-types. The combination does no good for it and leaves players wanting more. It's a shame because the concept of Camerupt is wonderful.
#2 - Whiscash
Like Camerupt, Whiscash's typing makes it an avoided Pokemon. It should be an Electric-type by its look, but it has a strange Water/Ground-typing. That makes it extremely weak to Grass-type moves.
Its best trait is that it will eat just about anything, alive or not. That gives it some personality, but it does not stand out as a Pokemon. There are many more that can do their job better.
#1 - Palossand
Palossand has the distinct honor of being an underwhelming Ghost-type and an underwhelming Ground-type. The sandcastle seems like an idea someone came up with, threw in the trash, then someone dug it out and decided to make it happen anyway.
It can grow a building's size, but without Dynamax, that can't happen in the games. It is just simply a looked over Pokemon without a real purpose.