Bastiodon

Sturdy
OHKO moves will fail.
Type Tier
Rock / Steel UU
Statistics
Min- Min Max Max+
HP
60
- 261 324 -
Atk
52
126 140 203 223
Def
168
334 372 435 478
SpA
47
117 130 193 212
SpD
138
280 312 375 412
Spe
30
86 96 159 174
Name Item Nature

Metal Burst

Leftovers / Focus Sash Brave
Moveset IVs
~ Curse
~ Stone Edge
~ Earthquake / Taunt / Toxic
~ Metal Burst
0 Spe
EVs
252 HP / 252 Atk / 6 Def

Metal Burst and Curse go together like soap and water. Switch this in on a Choice Bander or something and Curse. If your opponent goes to an Earthquake user, predict it and use Metal Burst. Taunt will help you predict, and is probably preferable—even if you manage to rack up a couple Curses, it's doubtful that you'll sweep. Toxic could also work. You can try to Burst stronger Earthquakes with Focus Sash.

Name Item Nature

Metal Sound

Leftovers Modest
Moveset EVs
~ Metal Sound
~ Flash Cannon
~ Thunderbolt
~ Hidden Power Ground
252 HP / 6 Def / 252 SpA

Bizarrely enough, Bastiodon has a good special movepool. This set has decent coverage and would work okay, if only Bastiodon didn't, you know, suck.

Name Item Nature

Fissure

Leftovers Adamant
Moveset EVs
~ Fissure
~ Stone Edge
~ Sleep Talk
~ Rest
252 HP / 252 Atk / 6 Def

This set is listed because it is the only set that actually makes sense on Bastiodon. Now its lack of offense doesn't matter, and Bastiodon does switch in pretty well. OHKO moves like Fissure are usually banned, though.

Other Options

Bastiodon learns a variety of standard moves, such as Toxic, Stealth Rock, and Roar. You can make a set out of these for a decent supporter, but there are other Pokémon that also do them, and are so much better—Aggron, for starters, or even Probopass.

EVs

Max HP and boost an attack stat if you plan to use one.

Opinion

Game Freak has this odd opinion where they seem to think Steel/Rock is a good tank/wall typing. It's not—even with Bastiodon's great defenses, Earthquakes still do large amounts of damage. Even in UU, Gligar can OHKO.

Counters

"Earthquake", but watch out for Metal Burst if you lack STAB, a boosting move, or a Choice item. Strong Fighting moves like Focus Blast and Close Combat are equally effective. Don't worry about which Pokémon is using the move—as long as it's not weak to Rock, you're probably in the clear. If the Fissure set comes out, you'll want an immune Pokémon not weak to Stone Edge—Skarmory, Gligar, Gliscor, anything with Levitate or any Pokémon with the ability Sturdy will do. Or you can just hope that you're luckier.