Power is a term with several meanings in Dinosaur King that differ between mediums.
In the arcade game, Power (or Strength in the English arcade version) is essentially a measure of the dinosaur's health. When entering battle, they have a health bar filled with the number listed here, and this is depleted by the opponent's Attack stat if the opponent wins a match-up. The Power of a dinosaur usually ranges between 1000 and 2000, and aside from "star players", are often based on how large a dinosaur is relative to other dinosaurs of its Attribute. (e.g. A small Water Dinosaur may have less Power than a large Wind Dinosaur despite the Water Dinosaur probably being bigger than the Wind Dinosaur, simply because most Water Dinosaurs are already bigger than most Wind Dinosaurs and it therefore wouldn't be fair to use absolute size across all dinosaurs as a determining factor.) Power/Strength and Technique are often inversely related, minimum of one alongside maximum of the other.
In the TCG, Power is instead a measure of the dinosaur's attack strength and the primary numerical statistic, merging the arcade Attack's function with the arcade Power's front-and-center position. A dinosaur's Power is combined with that of its Move Card and compared to the opposing dinosaur and Move's to determine who is the winner of the battle, and a tie counts as both losing. A dinosaur's Power is based on their Level, with a standard Power for each Level if no abilities, and then lowered (or raised) according to how helpful or easy to use a dinosaur's ability is to balance out the advantage (or disadvantage) the ability gives; more details here. Power ranges from 1000 to up to 2500; small form Special Dinosaurs (main dinosaurs) have 700-800 Power, and the Easter Set special egg cards have only 200 Power.