>>43567501its too fast to be good in trick room, too slow to be good outside of trick room. it has bad defenses and low hp so it will die from two not stab, regularly effective attacks (might as well be 1hko if from a stab or super effective). yes it has good attack stats, but its strongest (not two turn) STAB attacks are 80bp physical, 90bp special, 70bp physical, and 80bp special, and it won't be causing many flinches with needle arm or dark pulse with that low speed (or good luck getting two uses out of payback). yes it can use swords dance as well as nasty plot (which requires a turn to set up but good luck) to help deal with its attacking moves, and although swords dance sucker punch 70bp STAB will definitely pack a punch, your other coverage moves besides grass and dark would be fighting, poison (physical 80bp), electric (physical 75bp), and ground (physical 75bp) unless you just want to run 1 or 2 status moves.
Cacturne really has no purpose for that high special attack since both its stabs are no longer both special attack dependent and any other attack is from attack. Now, the only things it can do with that special attack are dark pulse, energy ball, and focus miss. Cacturne has the movepool of a physical attacker so... maybe it can use focus blast to take care of certain steel types but other than that, special attack is now just worthless on cacturne and even removing 65 special attack on cacturne and giving it to the other stats would still make cacturne bad, who is much more useful being immune to water instead of being immune to sandstorm.