Well that IS an interesting way to use Cacturne, but I see no reason to go mixed with it. The standard set is still just as useful, and can still set up Spikes pretty well.
Cacturne @ Leftovers/Yache Berry
Trait: Water Absorb
EVs: 80 HP / 252 Atk / 176 Spe
- Sucker Punch
- Seed Bomb
The Speed EVS let Cacturne outspeed max Speed base 45s (Golem) since most base 55s don't usually run max Speed (or else they run a +Spe nature regardless). Leftovers is the norm, but Yache Berry has situational use since at full health, it lets you live an Ice Beam from even Modest Ludicolo (you even have the tiniest of chances to survive an Ice Beam from +2 Timid White Herb Gorebyss). Seed Bomb is much more effective than Giga Drain simply because it hits much harder due to the Atk investment.