|Ability||If you have another Mech minion, this minion has Rush.|
If you have another Mech minion, this minion has Rush.
Note the wording: that Metaltooth *has* Rush, and does not *gain* Rush. Think of it as an "aura" buff, that disappears as soon as the condition is no longer met. It means that if you summon two Metalteeth on the same turn, then move and attack with one, the second will become exhausted when the first one dies.
The plural is "Metalteeth". :-)