Mysterious Larva vs Gravemind: who would win?

Mysterious Larva favored — Slight edge (~55%)

Mysterious Larva · Kaiju No. 8 · Base

Tier
HIGH 6-B, up to 6-A
Attack Potency
Large Country Level, up to Continent Level
Speed
Ftl
Durability
Large Country Level, up to Continent Level

Gravemind · Halo · Base

Tier
6-A
Attack Potency
Continent Level
Speed
Unknown
Durability
Large Building Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.