Like I said earlier, Suicune's best water attack is scald, so there's no good reason to use surf. Scald will also deal plenty of damage, even to opponents that resist it, after several calm minds. Suicune doesn't need ice beam or extrasensory for coverage. Tailwind is also pretty bad on it, as it usually takes much longer than 4 turns just to defeat one opponent. Because calm mind already raises its special stats, it needs physical defense EVs and a physical defense boosting nature much more than it needs special attack. It also needs protect and substitute, which are very effective at stalling when combined with pressure and leftovers.