Any half-brained Pokemon fan will tell you that Groudon and Fire Princess are a bad matchup because Groudon is pure Ground type outside of primal reversion. He created the continents of land on the world of Pokemon. His only association with fire is through the magma underground, which is why he gains the fire type only with primal reversion.
I submit pic related as a much better suited team up. I suppose an argument could be made for Toph, however.