maybe they could add custom pokes (we already have 4, can't hurt adding more, can it?) which we get when we breed certain pokemon, in this case, events. that way we the value of event pokemon would stay the same and this new idea can be implemented. sure it would take time to design these but hey, who cares as long as the feature would still be added. plus there are a buttload of pokefusions out there, we could take inspiration from some, like this! volcanion x necrozma!