Trucks are mysterious vehicles that live on the Vermillion docks. If you use Strength with a Lv100 Machop on the truck, you will get a Mew. Totally.
Before spriting Apsa, Sparkleaf used a truck with Unown letters to represent her in a comic. This later led into the truck in the two-part Team Luxrio story arc.
When delivering a shipment of "Whatever Kitsune's Favorite Food is," MysteriousVaporeon's truck evolved into a Mega Truck. It was able to Mega Evolve by resonating with MV's feelings. The Mega Truck desires the truth, and will run you over with THE TRUTH. However, they can be persuaded to temporarily forgive lies if the liar can play a particularly impressive saxophone solo.