Context: Riku is a boxer of Baba gym. Tokorozawa is a retired boxer of Baba gym. Ishigami is a retired boxer of an unmentioned gym. Tokorozawa beat Ishigami in the past. Recently, Tokorozawa asked a favour to Ishigami. Now also Riku is taking advantage of Ishigami's help. When Riku asks Ishigami about the match with Tokorozawa, Ishigami says:
負かす is a transitive verb, so I think 負かした俺 means "me who beat". From this sentence it looks like it was Ishigami that beat someone from Baba gym. Who is the subject and object of 負かした? Could you explain how this relative clause works?
Could you also confirm that どいつもこいつも is the subject of 頼りにしてく?
Here you can see the original page (Ishigami is the man with the shaven head).
Thank you for your help!