these are various meanings of phlegmatic

a. Having or suggesting a calm, sluggish temperament; unemotional or apathetic.

b. not easily excited to action or display of emotion; having a calm or apathetic temperament.. synonymes apathetic, stoic, cold-blooded, sluggish. Antonymes edgy, excitable.

LIVELY is therefore the opposite of phlegmatic from the options given above. it means to be;

a. Full of energy or alertness; vigorous or animated: a lively baby; lively eyes.

b. Characterized by much activity or excitement: