Preheat grill to medium. If using wooden skewers, soak skewers in a 9x13-inch pan of water for about 30 minutes.
In a small bowl combine 2 tablespoons olive oil, chili powder, salt, onion powder, garlic powder, cumin, and sugar.
Add salmon to a separate large bowl. Pour the oil and seasonings over the top of the salmon and gently toss to coat evenly.
To each skewer, alternate adding a cube of salmon with a cube of pineapple, leaving a little space in between each. (You can also add all salmon to a skewer to all pineapple to a skewer.)
In a small bowl combine the lime juice, oil, and garlic powder. Pour half of the lime oil into a separate bowl so you have two bowls of lime oil. Set aside one bowl for dipping.
Carefully brush the grill grate with 1 tablespoon olive oil. Place skewers on the grill directly over the heat.
Using one bowl of lime oil, brush the salmon kebabs on all sides. Cook for a total of 12-14 minutes, rotating and brushing the kebabs with more lime oil every few minutes. Skewers are done when the salmon reaches an internal temperature of 145°F.
Serve salmon kebabs with lime and the reserved lime oil (the second bowl) for dipping.