Toxapex's biggest advantage over Slowbro isn't his bug resistance, his stats, or tspikes. It's the fact that Slowbro is part psychic, making him weak to Dark moves and Ghost moves, that screws him over. Obviously Pex doesn't overshadow him or anything, but Slowbro being pursuit weak, knock off weak, and Ghost weak hurts his walling.
There's also the fact that Toxapex isn't grass weak like Slowbro is, meaning Pex can totally wall Charizard-Y and other things that pack surprise solarbeams... and Slowbro just dies.
There's also the fact that Toxapex isn't grass weak like Slowbro is, meaning Pex can totally wall Charizard-Y and other things that pack surprise solarbeams... and Slowbro just dies.