Honestly, I'm a bit weary of the whole 'zombie werewolf' mashup as a concept. It often feels like a writer trying too hard to be edgy by stapling two overused monster templates together. The evolution I'm more interested in isn't the creature's power level, but the narrative logic. If a werewolf is already a reanimated corpse on full moons, how does zombie-ism even manifest? Do they become a shambling wolf-man craving brains instead of flesh? It usually just becomes an excuse for a more grotesque, unkillable physical threat in action-heavy plots, losing the tragic curse angle of classic lycanthropy.
That said, I did read a web serial once that handled it with some clever body horror. The 'zombie' aspect wasn't viral, but a necromantic enchantment placed on a werewolf pack, so they'd keep regenerating to serve a lich lord. Their human minds were gone, but the wolf instincts remained, creating this eerie, relentless hunting pack. It worked because it explored the consequences rather than just the aesthetics. Most of the time, though, it's just a power-up gimmick.