SJCrew
Believer, going on a journey...
Colonial, I'm going to save Chou a bit of trouble in responding to you and point out some of the many major errors that deconstruct your entire post.
The first of them is Stealth Rock being absent in some of your calculations. Even in a metagame with Excadrill and Defog present, no one cites 2HKOs without Stealth Rock.
252+ Atk Life Orb Mamoswine Earthquake vs. 252 HP / 252+ Def Mega Venusaur: 146-173 (40.1 - 47.5%) -- 49.2% chance to 2HKO after Stealth Rock
252 Atk Life Orb Garchomp Outrage vs. 252 HP / 252+ Def Mega Venusaur: 160-188 (43.9 - 51.6%) -- guaranteed 2HKO after Stealth Rock
With regards to Tyranitar, you neglected to mention Sandstorm. Mega Venusaur's function is limited in Sandstorm because with Crunch, Sandstorm, and Stealth Rock damage in conjunction, nevermind Stone Edge, Tyranitar can outdamage Venusaur's measily 25% healing. CB Tyranitar is very good and should never be discounted in a debate. Because of these factors, Venusaur has trouble switching into all but the most defensive of Tyranitar.
Finally, Manaphy defeats Mega Venusaur with +3 Psychic. Thundurus-I can use Nasty Plot and Psychic as well, giving it the option to defeat Mega Saur without giving up coverage against most Dragons and Ground types, but I've never used it. I can personally attest to the effectiveness of Manaphy as a Mega Venusaur lure, however.
The first of them is Stealth Rock being absent in some of your calculations. Even in a metagame with Excadrill and Defog present, no one cites 2HKOs without Stealth Rock.
252+ Atk Life Orb Mamoswine Earthquake vs. 252 HP / 252+ Def Mega Venusaur: 146-173 (40.1 - 47.5%) -- 49.2% chance to 2HKO after Stealth Rock
252 Atk Life Orb Garchomp Outrage vs. 252 HP / 252+ Def Mega Venusaur: 160-188 (43.9 - 51.6%) -- guaranteed 2HKO after Stealth Rock
With regards to Tyranitar, you neglected to mention Sandstorm. Mega Venusaur's function is limited in Sandstorm because with Crunch, Sandstorm, and Stealth Rock damage in conjunction, nevermind Stone Edge, Tyranitar can outdamage Venusaur's measily 25% healing. CB Tyranitar is very good and should never be discounted in a debate. Because of these factors, Venusaur has trouble switching into all but the most defensive of Tyranitar.
Finally, Manaphy defeats Mega Venusaur with +3 Psychic. Thundurus-I can use Nasty Plot and Psychic as well, giving it the option to defeat Mega Saur without giving up coverage against most Dragons and Ground types, but I've never used it. I can personally attest to the effectiveness of Manaphy as a Mega Venusaur lure, however.