Originally Posted by Fat Zeburaika
Explosion is still 250 base power, it just loses the effect of halving the opponent's defense. In doubles/triples, when it's hitting more than one pokemon, the damage is multiplied by 3/4, not 1/4.
Ok, that makes much more sense! It still seems compeitively viable, even with the defense-halving nerf still in effect. Sorry if this should have gone in the Q&A thread.