Dodrio is an excellent Pokemon when it comes to physical sweeping, whether it's using a Choice Band or a Flail set. Thanks to its awesome STAB Drill Peck, Dodrio can be a true monster if its teammates can take out physical walls that stop it short. However, it's really fragile and won't be switching in on much.
Dodrio has excellent Speed and Attack, which makes it an ideal Choice Band user. However, as it is fairly fragile, it will have difficulty switching in. It is a fairly good lead, but is at its best late-game, when it can quickly fire off powerful attacks. Dodrio is a pretty mean physical sweeper, as it gets STAB on three of its attacks. Hidden Power Ground hurts Magneton, Jirachi, and Metagross on the switch-in, but Dodrio should not stay in unless it will surely OHKO the foe. Hidden Power Fighting is stronger against Tyranitar, but is inferior as Hidden Power Ground will do just fine while maintaining a perfect Speed IV.
Maximize Attack and Speed because Dodrio will not stay in for long anyway. A Jolly nature is useful to surprise opponents expecting to outrun Adamant variants, and the Choice Band somewhat makes up for the drop in power.
As it gets STAB on Flail, Dodrio can easily sweep a team if used correctly. This variant of Dodrio is powerful, but is a bit harder to use than the standard Choice Band set. Liechi Berry boosts Dodrio's attack power, but Agility is a must in order to ensure a sweep. Alternately, Dodrio could use a Salac Berry, run at least 112 EVs, and drop Agility for another move. Quick Attack is its best choice to help against enemy Flail users.
Similarly, use maximum Attack, and dump the rest of the EVs in HP for greater overall bulk. If using Agility, run minimum Speed, but more Speed is a possibility. Salac Berry variants should aim to hit a Speed stat of 264 after a boost; this requires 16 EVs if using a Jolly nature, and 112 with an Adamant one.
Baton Pass is a great option as Dodrio can pass along a Substitute or some Speed to really help a teammate set up. It can also use Baton Pass on the first turn to scout out your opponent's Dodrio counter; if it is Skarmory, bring in Magneton for an instant KO. Similarly, passing to Dugtrio can end a weakened Tyranitar or Metagross switch-in. Endeavor can be used in conjunction with Quick Attack to make short work of opposing Pokemon, but Tyranitar's Sand Stream can prove troublesome. Haze can remove an opponent's boosts, but it is fairly useless overall because Dodrio is fragile. In general, Dodrio's base 110 Attack and base 100 Speed stats mean it's best off with an offensive moveset.
Checks and Counters
Skarmory and Forretress, two of the most common physical walls, can handle Dodrio with relative ease—watch out for Magneton, however. Tyranitar's Sand Stream wears down Dodrio, and Tyranitar himself resists both Dodrio's STAB moves. However, Choice Band Hidden Power Ground can 2HKO it, and Hidden Power Fighting will OHKO. Metagross can shrug off nearly everything Dodrio throws at it; even Choice Band Hidden Power Ground might not 2HKO him. Regirock is one of the best counters as well, because neither Hidden Power will do much damage. The latter three can easily OHKO Dodrio with their STAB moves.
Gengar can come in on Normal attacks and either Thunderbolt Dodrio into oblivion or cripple it with Will-O-Wisp. Choice Band Drill Peck will OHKO him more often than not, though, and Flail sets usually pack Hidden Power Ghost. Dusclops is slower but more defensive, and has the same immunity to Normal attacks; he can burn Dodrio and heal off damage with Pain Split or Rest. Just about any hit, especially STAB or super effective ones, will cripple—if not KO—Dodrio, as its defenses are abysmal at best.