The Two of Pentacles is a card of change and it is trying to achieve balance during or after a phase of transition or a temporary situation. The Six of Wands, called "Victory", bears the element of interaction. It describes a situation that cannot exist without the contribution of (at least) two people and which usually results in a "win-win" outcome. The combination of the Two of Pentacles and the Six of Wands is about balancing different energies/situations in an effective way.
To understand the elemental relationships between the cards, we should always take into account their actual meanings.The elements of these cards are Earth (Two of Pentacles) and Fire (Six of Wands). Fire is cleansing and energizing to Earth. We could see it as the high energy particles that hit our planet and give birth to life. For better or worse, the energy of this Six will strengthen the energy of the Two of Pentacles in a dynamic way.