From Blaseball Wiki

A screenshot of Evelton McBlase II with the Base 1 evolution.

Evolution is a mechanic that was originally introduced during the Season 2 elections as a Decree. During the Season 2 election, the Evolve Decree stated "The team with the most fans will Evolve." While it did not pass, Evolution as a mechanic returned during the Season 12 elections as the Based Evolution Decree, stating "Every Third Championship a Team wins will cause the Team and its Players to Evolve. Players that round the phylogenic Bases will get to go Home." Base Evolution was voted in with 247,049 votes, or 53% of all Decree votes.

Based Evolution

For every third Internet Series championship a team wins, each player on that team's current active roster (i.e. not including Shadows) advances by a single evolutionary "base" (the first evolution being from "Base" to "Base 1"), and the team is granted a unique permanent modification thematically related to the specific team. Player evolution is a one-off effect – unevolved players transferred to evolved teams will not evolve, and evolved players transferred to unevolved teams will retain their evolutionary level.

If a player has the Base 1 evolution, their first star in each category is protected, indicated by that star turning gold and gaining a circle around it. The player then can never have their stars reduced below that level, meaning Base 1 players will always have at least one star in each stat category. As of the introduction of the Items tab at the end of Season 15, evolved players also unlock a number of additional item slots corresponding to their evolution – for example, Base 1 players have two available item slots instead of one.

List of Evolved Teams

Team Times Evolved When Team Modifications
Atlantis Georgias 🔱 1 Unknown; by Season 12  Undersea
Baltimore Crabs 🦀 1 Unknown; by Season 12  Carcinization
---- --------- 🛠️ 1 Unknown; by Season 12  Maintenance Mode
Ohio Worms 🐌 1 Unknown; by Season 12  Bottom Dweller
Hades Tigers 🐅 1 Season 12 Election  Ambush
New Hampshire Eggplants 🍆 1 Unknown; by Season 22  Nightshade[note 1]
Canada Moist Talkers 🗣️ 1 Season 23 Election  Flood Bath
  1. Assumed