The Idea of the band is to ensure that typhlosion gets at least one howl in, to ensure some real damage (due to the fact that its defenses leave much to be desired) but a focus band might work just as well, if not better. More than likely, typhlosion wont be able to take a crit-quake and so, to make up for its poor defense, it needs something to ensure that it survives. if you get a second howl off (assuming you get lucky and the opponent wants to switch to counter typhlosion better), you can smash water types with thunderpunch. most standard pokemonll take a hard hit from flare blitz or earthquake.
thinking on it now tho, if you have a baton passer that can pass Atk, Def, Sp Def, or Spd, they all help typhlosion survive alot longer for much more sweeping. This set is actually designed to be the head pokemon of a team tho, b/c in standard, typhlosion is very rarely seen (so i hear). opponent sees it, they switch to try to counter it, and it survives long enough to use 2 howls, doubling its attack power. When its about to die, or if you need a kamikaze attack, blitz it out. Even against gyarados, typhlosion can strike hard and fast with thunder punch, and he resists steel. Being that, If played by the strategy above, hes sent out first, theres no time for spikes, stealth rock, or any of the like. as a fire type, he cant be burned either, so no burn atk cuts. the only real way to take this typhlosion is to have a pokemon that can resist electric, fire, and ground well, and that can take a few hits or reduce its atk to cushion a few of the blows.
EDIT: Shell Bell. Just Thought of it, it may sound bad, but if you get off the extra howls, even if you take a bit of damage, you can sweep it all back, literally. they send out gyarados to counter typhlosion, you have normal atk, (howl - Intimidate) thunder punch the gyarados, then it hits typhlosion, then at the end of the turn, you get back an 8th of what you lost from gyarados. the second thunder punch should be enough to finish gyarados off, thus you heal 1/4th of your total HP and possibly have a boosted attack to keep it up with. Also, if you DO take a hit and it brings HP down to the point of triggering Blaze, flare blitz becomes a potential OHKO to even neutral pokemon , and can be used nearly indefinately (with PP limits of course) with shell bell healing every turn.