Hmm. Not sure that Swagger and Metal Burst go together very well... sure, you're increasing your foe's Attack, but the confusion makes it so that you can't assume a hit for awhile. You might end up wasting that valuable time with a confused foe... seems a little risky to me, although I see the point behind it.
It seems like you're going for an Annoyer set... if you're going to do that, I'd go all the way with it. Maybe swap Metal Burst for Attract in an attempt to hamper your opponent even further. Block and Toxic are a nice combination, so those should be kept on an Annoyer. As for Swagger, you might drop that for Torment or something if the Attack boost proves to be a problem. You could also go with Protect to take more advantage of Toxic. But I'd test Swagger thoroughly first; it may not be an issue with Bastiodon's high defenses.
Anyway, that might look as follows:
Swagger/Torment/Protect
Block
Toxic
Attract
You could also try Bastiodon as a Tank or a Tank/Annoyer. A Tank/Annoyer might look something like the following:
Rest
Double Team/Sleep Talk/Block/Protect/Swagger/Taunt
Toxic
Double Team/Sleep Talk/Block/Protect/Swagger/Taunt/Filler
Sleep Talk's a lot more helpful if you have an attack as your fourth move... otherwise it's pretty much useless. You could also go with defense-boosting moves like Iron Defense, or even throw in an Endure if you think you can get an extra move out of it. This is pretty much a mix-and-match moveset.
As for a regular Tank, you might try...
Iron Defense
Earthquake/Return
Ice Beam/Thunderbolt/Flamethrower/Metal Sound
Toxic/Captivate/Attract/Filler
...or...
Rest
Sleep Talk
Ice Beam/Thunderbolt/Flamethrower/Toxic/Metal Sound
Earthquake/Return
Set 1: Brace yourself and bash away. Toxic poisons, Captivate could help you against Special attacks (although I'd almost go with Attract in that case), or another attack may provide more coverage if you're lucky.
Set 2: Basically, Rest when you're hurt and Sleep Talk into powerful moves. Metal Sound could weaken your opponent for the EQ or Return, while the elemental beams give you more coverage against different Pokemon. Toxic, as always, could give you an edge in longer battles.
So, yeah. Maybe those half-baked ideas will help you in some way. I think your moveset is pretty good; my only real concern is the unreliability of Metal Burst. Then again, I've never been fond of Counter tactics, either, so maybe it's just my personal bias. *shrugs*