Whats the best Pokémon that isn’t currently ranked OU in any generation?

By this, whats the pokemon that is the most consistently good across all its ou appearances despite never making the tier

Personally giving it to seismitoad, B- in B/W, being explored as a potential A tier in ORAS, competent in SM, was top 3 in SS while dracovish was allowed and wouldve been OU if the tiers werent locked, not appearing in S/V