Yes.
As a verb team means to match or coordinate. eg
Three artists teamed for the exhibition.
The phrasal verb team up is probably more common.
It is an action verb.
The action verb is 'training' or, including auxiliary verbs 'should have been training'.
began is an action verb, not a linking verb.
what follows a linking or action verb
"Sent" is an action verb. It shows an action, such as "she sent an email."
It is an action verb.
action verb
Action verb
Action verb
An action verb
The verb stay is an action verb.
Yes,waiting is a action verb