An experiment showed that Japanese speakers' judgement of Pokémons' evolution status on the basis of nonce names is affected both by mora count and by the presence of a voiced obstruent. The effects of mora count are a case of counting cumulativity, and the interaction between the two factors a case of ganging-up cumulativity. Together, the patterns result in what Hayes (2020) calls 'wug-shaped curves', a quantitative signature predicted by MaxEnt. I show in this paper that the experimental results can indeed be successfully modelled with MaxEnt, and also that Stochastic Optimality Theory faces an interesting set of challenges. The study was inspired by a proposal made within formal phonology, and reveals important previously understudied aspects of sound symbolism. In addition, it demonstrates how cumulativity is manifested in linguistic patterns. The work here shows that formal phonology and research on sound symbolism can be mutually beneficial.