Lenna's only protection against Fire type attacks is her own typing, Water. So between Hibiscus' defensive maneuvers, Light Screen, Water Sport, and her natural resistances, Lenna is mostly unscathed from Heatran's attack. Maybe a few burns here and there, but nothing severe enough to worry about at the moment.

"Gogo, use Reflect. Gilgamesh, Scald."

Leaping into action, the Mr. Mime tosses up a second shimmering barrier in front of the group to help bolster their defenses even more. The Panpour, for its part, takes advantage of all the heat in the air to let loose a boiling hot water attack toward the great beast.

Lenna only hopes that their efforts would be enough.