Mindlink Mech's second ability triggers as its crew ability resolves for the first time each turn.

Mindlink Mech's triggered ability can target only a creature that was tapped to pay its crew cost this turn.

If a continuous effect that isn't a copy effect is modifying Mindlink Mech's power, toughness, or types, that effect will continue to apply to it after it becomes a copy.

Mindlink Mech copies exactly what was printed on the original creature (unless that creature is copying something else or is a token; see below), except that it also has Mindlink Mech's types and is 4/3. It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or any Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, or so on.

If Mindlink Mech becomes a copy of a creature that is copying something else, it becomes a copy of whatever that creature is a copy of.

If the creature is a token, Mindlink Mech copies the original characteristics of that token as stated by the effect that put the token onto the battlefield. It doesn't become a token.

If a player crews Mindlink Mech with a nonlegendary permanent that is not normally a creature or Vehicle, the resulting permanent Mindlink Mech becomes is a 0/0 artifact creature and will usually be put into its owner's graveyard. This is because a copy effect can't set the power and toughness of a permanent if being a creature isn't part of that permanent's copiable characteristics. The crew effect is then applied after the copy effect, and it becomes a creature with no defined power or toughness, so both are set to 0.