Well, I kind of disagree on the point you make about Lucky Chant being useless. It is enough for Pokémon with Nasty Plot or Swords Dance to set up but also very beneficial for others, for example a Registeel with Amnesia/Curse would benefit a LOT from a few turns with no Critical Hits, reducing your risk significantly. Those turns might be all you need to get your defences high enough so you can recover HP + Sub faster than they can take it down.
This team was only meant as an original example team for getting 100 wins, not an invincible one, so it is obviously not perfect. Having said that, a +6 Garchomp is pretty brutal in the Tower and can kill of most things with Outrage or Earthquake. Only Glalie 390 and Lapras 356 have Ice Shard after battle #49, so I doubt Ice priority will 'wreck' this team. The only Pokémon with more speed and good Dragon moves are Sceptile 765 and Aerodactyl 851. Of the 2 Pokémon outspeeding Garchomp holding a Focus Sash, two are Electrics with no SE moves. The remaining Pokémon outspeeding Garchomp are Electrics or spread out fairly evenly over which trainers use them. This means it is less likely you're going to face 2 threats in a row than if say all your threats were Ice Pokémon and any Ice trainer has a good chances of having two major threats. At some stage you will obviously get screwed by something like Brightpowder misses but that is something that happens to most teams. Yet overall I still think this team would be adequate to do what it was designed for, getting 100 wins.