So you've never played a good Sneasel/Slowking deck. Hm.
And Wigglytuff is a stage 1. Not a stage 2.
Wiggly requires MORE energy, Wiggly can NOT be played first turn, Wiggly has a retreat, Wiggly requires more FOCUS on to keep safe, up, and running, Wiggly (Without the aid of trainers) has a MAX of 60 (Unless you'd care to Poison him with Darkness), the fact that he does an assured 60 hardly makes up for these things.
Y'know why people like Sneasel? Although it requires 6 coin flips, mathematically, you'll most likely get 60 (3/6 heads), AND the ability to use Darkness energy, and a max damage total of 160 (That's excluding trainers or other powers). Heck, TWO heads out of Six will result in 60 damage with two Darkness Energy. NO retreat, NO weakness, LOW energy cost, EXTREMELY quick (basic), and considering how WELL it goes with Slowking. Slowking protects your Special Energy, Sneasel tears through everything your opponent throws out. Focus Band keeps it alive, your opponent doesn't have the CHANCE to use large enough Evos that stand a chance of living long. You can slap these things down, and have them ready to do an easy 80+ damage in just two turns.
Remember, Wigglytuff will MAX out at 60, Sneasel will AVERAGE 60.
Most people LIKE the idea of being able to slap down a basic that's strong enough to stop ANYTHING in just two turns, and easy to keep safe due to no weakness and no retreat.