For reference since I don't think he has a stat topic entry:
Whelk is 120% average speed and has slow, but his HP sucks (1600 to a 280 average, works about to about 65% PCHP to me, YMMV) and his damage is a mid 9HKO (11-12% to average).
He also does that thing with the shell which an intelligent opponent won't run into. Any stupid puny opponent who does attack the shell (or who only has MT) will get fried by high 2HKO Bolt 2 counters.