For the most common baton pass teams, a team someone suggested I run had a landorus-i with EP/SludgeWave/Psychic and it absolutely messed with baton pass as long as the didn't lead Smeargle. Dragon dancers like Mega Tyranitar also seem to mess with baton pass, as Scolipede leads and protects thinking standard SR lead TTar. One dragon dance and you're in business to mess with them even if they get an iron defense boost off. Personally, Lando is much more consistent given each team only has one early game Special defense booster and two early game defense boosters.
Hmm, looking at the damage calculations now and I don't think either of those can beat standard Defensive Baton Pass teams if they play correctly. Here are the calculations:
Landorus
Lead Landorus vs Scolipede. Scolipede gets +4 speed and passes to Sylveon:
252 SpA Life Orb Sheer Force Landorus Sludge Wave vs. 252 HP / 252+ SpD Sylveon: 192-229 (48.7 - 58.1%) -- 58.6% chance to 2HKO after Leftovers recovery
Sylveon then gets off a Calm Mind:
252 SpA Life Orb Sheer Force Landorus Sludge Wave vs. +1 252 HP / 252+ SpD Sylveon: 130-153 (32.9 - 38.8%) -- 6.7% chance to 3HKO after Leftovers recovery
Sylveon passes to specially defensive Espeon, who tanks the hit and then 1HKOs with Stored Power:
252 SpA Life Orb Sheer Force Landorus Earth Power vs. +1 248 HP / 252+ SpD Espeon: 114-136 (34.2 - 40.8%) -- 59.1% chance to 3HKO after Leftovers recovery
+1 0 SpA Espeon Stored Power (140 BP) vs. 4 HP / 0 SpD Landorus: 340-402 (106.2 - 125.6%) -- guaranteed OHKO (this is with +4 speed, which is easy to get)
OR, Sylveon/Espeon gets off a Calm Mind and then passes to Vaporeon:
252 SpA Life Orb Sheer Force Landorus Earth Power vs. +1 252 HP / 0 SpD Vaporeon: 160-188 (34.4 - 40.5%) -- 52.5% chance to 3HKO after Leftovers recovery
+1 4 SpA Vaporeon Scald vs. 4 HP / 0 SpD Landorus: 338-402 (105.6 - 125.6%) -- guaranteed OHKO
Furthermore, Landorus can be stopped by a Focus Sash Smeargle with Spore.
Now lets look at
Mega Tyranitar:
Turn 1: Scoli subs, Tyranitar Dragon Dances (an experienced Baton Passer will never protect vs Ttar / Dragonite / Scizor leads because they can setup and scolipede is fast enough to Sub first).
Turn 2: Scoli uses Iron Defense (now at +2 def, +2 spe), and Tyranitar uses Dragon Dance as well (now at +2 atk, +2 spe).
Turn 3+: Scoli uses Iron Defense, and is now beating Tyranitar in boosts. Eventually, scoli will reach +6 def, +4 spe with a sub vs a +4 atk, +4 spe Ttar. Or scoli will be without the Sub vs a +3,+3 Ttar.
Going into Vaporeon gives you three chances to Scald Burn Ttar before you die. If you get at least 1 burn Ttar dies.
4 SpA Vaporeon Scald vs. 252 HP / 4 SpD Mega Tyranitar in Sand: 108-128 (26.7 - 31.6%) -- guaranteed 4HKO
Going into Smeargle works if the Substitute is still up (and then you can spore).
Going into Defensive Zapdos work as well to Roar works as well:
+4 252+ Atk Mega Tyranitar Stone Edge vs. +6 248 HP / 252 Def Zapdos: 282-332 (73.6 - 86.6%) -- guaranteed 2HKO after sandstorm damage and Leftovers recovery