Peacewalker Colossus

If a permanent becomes a copy of a Vehicle, the copy won't be a creature, even if the Vehicle it's copying has become an artifact creature.

If an effect causes a Vehicle to become an artifact creature with a specified power and toughness, that effect overwrites the Vehicle's printed power and toughness.

Once a player announces that they are activating a crew ability, no player may take other actions until the ability has been paid for. Notably, players can't try to stop the ability by changing a creature's power or by removing or tapping a creature.