Only Heatran, Infernape, and Volcarona are relatively safe Fire type switch-ins.
I know from experience that 4/0 Heatran is OHKOd by Jolly LO Low Kick after Rocks (252Atk Life Orb Weavile (Neutral) Low Kick vs 4HP/0Def Heatran (Neutral): 94% - 111% (306 - 360 HP). Guaranteed 2HKO. 66% chance to OHKO.), and 252/0 Heatran takes a minimum of 79% from the same Weavile, so Heatran is only safe if Weavile is either Choiced or lacks Low Kick.