RE: The D/P/P Questions and Answers Thread
Base power is what the relative power of the move is. The higher the number is, the more damage it will cause.
For example, Tackle (a move most starters begin with) has a base power of 35. You can examine this yourself by going into the Pokemon info window.
Most (offensive) moves in competitive battle will have base powers that average in the 80s. T-Bolt, Ice Beam, Flamethrower, and Surf all have base powers of 95, and thus are quite powerful moves. Dragon Pulse and Psychic have 90; Shadow Ball and Energy Ball have 80; Grass Knot has a variable base power dependent on the target's weight (but it caps at 120) - and so forth. Each move states what base power (and accuracy) it has when you examine it. (Support moves like Helping Hand and Dragon Dance do not have a base power as they do not deal damage.)
102 BP is quite high, just barely surpassing Earthquake's 100. And since Snorlax gets STAB on Return, that is another x1.5, giving it a theoretical base power of 153. And Snorlax is not only powerful, but sturdy. So expect it to do a lot of damage - especially after a Belly Drum.