Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Perhaps a Bug/Ground type would be able to boost sun a bit.
Sun can remove the water weakness, while this pokemon could tank some of the thunders that rain teams love to throw around and tank some of the earthquakes (and possibly rock type moves too) that many fire type mons can't handle...