Airachnid Bird vs Shorekeeper: who would win?

Shorekeeper favored — Slight edge (~55%)

Airachnid Bird · Transformers · Base

Tier
5-A
Attack Potency
Large Planet Level
Speed
Subsonic, up to Speed Of Light
Durability
Large Planet Level

Shorekeeper · Wuthering Waves · Base

Tier
5-A, up to 2-B
Attack Potency
Large Planet Level, up to Multiverse Level
Speed
Sub-Relativistic+
Durability
Large Planet Level

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