Sudowoodo

Type Tier
Rock UU
Statistics
Stat
HP
70
343
Atk
100
298
Def
115
328
SpA
30
158
SpD
65
228
Spe
30
158
Name Item

Physical Attacker

Leftovers
Moveset
~ Curse
~ Rock Slide
~ Earthquake
~ Selfdestruct

Sudowoodo is the only pure Rock-type in the game. But that's not really a good thing; Ground/Rock gives STAB on Earthquake at the expense of being weaker to Grass, Ice and Water moves. Anyway, Sudowoodo is just an inferior Golem, and you need to use it as such. Switch in on a Normal move, start Cursing up and hit with what you can. Explosion when you're done. Sudowoodo's only good moveset, really, works pretty well in the underused environment and, because of the lack of Ground typing and average Special Defense, he can actually take a Surf or two and live to Explode. But like I said, inferior Golem/Rhydon, he just isn't all that good.

Name Item

Mixed Attacker

Leftovers / Miracleberry / None
Moveset
~ Selfdestruct
~ Rock Slide
~ Thunderpunch
~ Fire Punch / Ice Punch / Thief

This is a comedy set, sure (meaning you shouldn't expect it to work), but you might suprise and paralyze a Water-type switch in, or freeze/burn a Grass-type. Same principle of Exploding when you're going to die. Thief is always nice on bad Pokémon, use it with Miracle Berry probably, to absorb a status and then Thief Leftovers.

Other Options

Obligatory mention of Sleep Talk—everything can use that though, but Sudowoodo certainly isn't particularly good at it. Sandstorm stinks but every Rock Pokémon *can* use it if they want. Toxic is nice for a beat down Pokémon like Sudowoodo, but there is no room for it in its moveset. Psych Up could be put over Curse to surprise a Curselax with Fire Blast and proceed to sweep (not really, though) a team, or at least damage them slightly. Curse Rollout is funny, and can actually do major damage to non Ground/Steel-types. Obviously, Steelix, Rhydon and pals laugh. Hidden Power Bug for Celebi/Exeggutor if you don't want to explode on them.

Opinion

I've always liked Sudowoodo, couldn't really tell you why, but I like the fake tree. He's the only pure Rock-type in GSC, before the days of Nosepass and Regirock, and that's a plus in some ways, though it mostly stinks, and he certainly wishes he was the first Grass/Rock instead (he looks like a Grass/Rock, anyway). An inferior Golem/Rhydon who can't do much besides Curse and Explosion, but he's accepted in the underused environment unlike the other two, and he can actually do okay there. All in all a cool Pokémon.

Counters

Suicune, Vaporeon, and other strong Water-types will force him to Explode (which can be good or bad depending on whether they predict the Explosion), Exeggutor, Celebi, Meganium, Tangela and other strong Grass-types have the same effect, Golem, Rhydon and Steelix will Roar it, Counter it or beat it in a Curse war, Skarmory will Whirlwind it out or Toxic it, etc.