[Sumac]

I feel like, if she was really called "Wapeach", it would have been more out of tradition, rather than pun.

As for the concept its totally lacks "evil" vibe.
She doesn't look like a femme fatale or a brat, so its hard to imagine how she would be compared to Wario and Waluigi in "evilness".
Also, she looks very generic. While looking at her counter-parts I can instantly tell they are supposed to be part of a Mario franchise, this version of Peach, can come from any other series.

They should have leaned into more gothic or bratty image. Or preferably, just keep Peach her regular age and built from that. No need to give her spikes, crooked nose or eyebags, just something channeling "bad attitude".