Dusk Legion Dreadnought

When a Vehicle becomes a creature, that doesn’t count as having a creature enter the battlefield. The permanent was already on the battlefield; it only changed its types. Abilities that trigger whenever a creature enters the battlefield won’t trigger.

Any untapped creature you control can be tapped to pay a crew cost, even one that just came under your control.

You may tap more creatures than necessary to activate a crew ability.

Vehicle is an artifact type, not a creature type. A Vehicle that’s crewed won’t normally have any creature type.

You may activate a crew ability of a Vehicle even if it’s already an artifact creature. Doing so has no effect on the Vehicle. It doesn’t change its power and toughness.

Each Vehicle is printed with a power and toughness, but it’s not a creature. If it becomes a creature (most likely through its crew ability), it will have that power and toughness.

Creatures that crew a Vehicle aren’t attached to it or related in any other way. Effects that affect the Vehicle, such as by destroying it or giving it a +1/+1 counter, don’t affect the creatures that crewed it.

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.