To Dragonite with Max Defense it would do between 330 and 388 which is an OHKO without lots of HP EVs. With that Nature no evs in defense then an OHKO. However if this was Gen V and he had multi-scale he could potentially survive with more defense or HP EVs.
To Salamence with Max Defense it would do between 367 and 432 which is definitely an OHKO unless it has max HP as well in which case there would be a small chance of survival, so with the nature you are suggesting it would OHKO it twice XD. If he had intimidate effect Mamoswine then it would still OHKO him.
To Garchomp with Max Defense it would do between 330 and 388 which is an OHKO without HP EVs. But with that nature and no EVs in Defense and HP then it is an OHKO no doubt.