If you read the manga you wouldn't need to ask that question. He said he would use EJ to make sure Aizen went down. Not that he needed it to win. Later he said Aizen was naive to think he could win, even WITHOUT RJ. How does Baraggan's arrogant ass stand any chance?
Yamamoto should be able to overpower Respira because of superior Reiatsu.
Actually, Yamamoto should be able to destroy Barragan before he releases, seeing that they start sealed.