Hideki, let me tell you, back then he couldn't get used to being here at all, and he'd sulk all the time.
Literal
Hideki-[exasperation-ったら], at-that-time [topic-は] utterly-[intensified-全っ然] here [dative-に] not-accustomed-[and-て][confirmation-ね], constantly was-sulking-[contracted-てた][nominalizer-の][feminine-よ].
Casual feminine reminiscence. ~ったら ('expressing mild exasperation or affection') attaches to a name to mean 'oh, X!' — as in 'that Hideki, I tell you!' 全っ然 is the intensifier 全然 with a small っ inserted for extra emphasis (drawn-out initial consonant). ふてくされる ('to sulk, to be in a bad mood, to pout'). しょっちゅう ('constantly, always'). てた is contracted ていた. The feminine なのよ ending.