There are a few flaws with this.
I would like o point out that if you are using Showdown there is a clauses preventing this strategy. It's the baton pass clause which was recently introduced, which limits Baton Pass to being on up to 1 Pokemon in a team from memory.
Apart from this;
- Mean Look's effect runs out the moment you use Baton Pass. This means they are free to switch out when you go to Drifblim into something which hits you for major damage. Even with a stockpile up, Drifblim would not be wanting to take powerful super effective STAB. Ghost types are also not affected by Mean Look. This single point breaks down most of your strategy, since it appears you're relying on T-Wave and Flash lasting throughout the entire match.
- Taunt breaks your whole strategy down
- Roar and Whirlwind.
- Any fast Pokemon carrying Substitute
By this I mean "Ok so I paralyze my opponent, use flash 2 times". If the opponent at the start outspeeds you, gets up the Substitute which blocks both Thunder Wave and Flash.
- Any Ground, Electric or Pokemon with Volt Absorb/Lightening Rod will be able to take the Thunder Wave
- Volt Switch and U-turn are able to force a switch for the user, even with Mean Look.
- Magic Bounce quickly stops your Flash strategy.
- Infiltrator. This ability allows the user to hit through Subs.
- Haze. Hits through Substitute, removes all stat boosts
- Sound-based moves. All of those kinds of moves are able to hit through substitutes, as of Gen 6.
- Clear Body stops Flash. Prevents all stat drops.
- Aerial Ace, Aura Sphere and all moves that will always hit are able to bypass Flash, since they ignore accuracy modifiers.
- Red Card. The moment you hit a Pokemon with the item Red Card, you get forcibly switched out even if you're behind a substitute. Not good for Octillery.
- Crits. Bypass your SpD boosts, hit you for 1.5x of normal damage. Dang, that's gotta hurt.
- Blissey. You have no way of breaking that pink blob down. Protect + Wish stalls you, can break down Octillery's subs with Seismic Toss.
+6 252+ SpA Octillery Surf vs. 252 HP / 252+ SpD Blissey: 324-382 (45.3 - 53.5%) -- 1.2% chance to 2HKO after Leftovers recovery