。
Every last one of them is an idiot.
Literal
Every-last-one fools [only-ばっかり][copula-だ].
どいつもこいつも is a contemptuous group reference — 'every last one of them,' literally 'this guy and that guy alike,' with こいつ/どいつ being rough demonstrative pronouns for people. ばかばっかり 'nothing but fools' uses ばっかり (casual ばかり). Short, blunt, and angry — pure frustrated venting.