Well there are quite a few to choose from:
- Nidoking and Nidoqueen: probably the most notable in the Johto region, and not that hard to get since you come across several moon stones in the story. Nidoran of both genders can be found on routes 35 and 36
- Quagsire: great since he only has one weakness and can deal out some pretty damaging physical moves such as Earthquake and Ice Punch to cover his weakness. Wooper can be found on route 32
- Piloswine/Mamoswine. This is the ground type I would recommend because of the added Ice Type. The last gym in Johto is dragon type, and the most effective way to beat him would be by using an ice type. Since you want a good ground type, why not go two in one and be ready for that final gym too? Swinub can be found on the Ice Path
Another ground would be Rhydon, which can be evolved into Rhyperior using the Protector found in Mt. Mortar. Rhydon and Rhyhorn can both be found in the Safari zone and on Victory Road.
If you're REALLY early in the game just get a good ol' Geodude! Although I wouldn't usually use a Golem (being WAY too OU) they're pretty good for in-game play.
Hope this helped!