Feraligatr in BW has a quite unique niche for being ridiculously strong for a rain sweeper. It abuses torrent perfectly because it has respectable bulk which often lets it get up a swords dance and hitting torrent in the same turn. A +2 stab boosted rain boosted, torrent boosted, mystic water or even life orb boosted aqua jet is (don't quote me on the number because it's from the top off my head) stronger than a 300 base power attack. There is even a rather famous replay of a feraligatr being the mvp in a final match of the OST (it's gr8astard vs DestinyUnknown game 1, you can find it on youtube). Basically priority and the ability to hit celebi/jellicent with crunch are what give g8r the niche over gyarados.