Mendicant Core, Guidelight

If an effect needs to know what a player’s speed is and that player doesn’t have a speed, their speed is considered 0.

A resolving copy of a permanent spell becomes a token, so the token isn’t “created.” Effects that care about a token being created won’t interact with a token that enters the battlefield from Mendicant Core’s last ability.

Your speed doesn’t change until a spell or ability says so, such as the inherent triggered ability that cares about opponents losing life during your turn. Notably, losing control of permanents with start your engines! doesn’t affect your speed.

Each player tracks their speed (or lack thereof) separately. Increasing your speed has no effect on whether another player has speed.

A player “has max speed” if their speed is 4.

“Max speed — [ability]” means “As long as you have max speed, this object has [ability].” If the granted ability functions in a zone other than the battlefield, the max speed ability does too.