As something with a fairly strong Volt Switch, he pairs really well with things that have Intimidate. Arcanine, Gyarados, Landorus-T, and Salamence all have some offensive and defensive synergy. Gyarados, Lando, and Salamence all can come into ground moves aimed at Heliolisk. Heliolisk can come back in to absorb water moves aimed and Lando or Arcanine. A good VoltTurn team can be made with Heliolisk as an offensive pivot.