Two Saibamen Potara fused vs EoZ Yamcha
I think that, if Gero's lines in the android arc aren't bullshit, Yamcha wins. If they are, the Saibaman stomps.
Super Saibaman- (1,200 + 1,200) x 100 = 240,000
Yamcha (logical)- 60,000
Yamcha (Gero-wanked)- 1,800,000
I currently lean towards the Gero-wanked side. Gero-wanked Yamcha couldn't even be beaten by a Saibaman fusion going by A x B, though the Saibaman could draw him with the suicide explosion.
Two Saibaman danced fused vs EoZ Yamcha
Filler Yamcha vs Freeza/Cell (pick forms) Yamcha is also free from the universal law of he has to lose because he is Yamcha
Filler Yamcha is wanked as fuck, but judging by Tenshinhan's fight with Trunks in Movie 13 and Olibu's fight with suppressed Pikkon, he's still only high base saiyan tier. He gets annihilated by either of them. The only possible diversion from the manga (assuming the highest reasonable estimate for Yamcha) is that Freeza would have to power up past his initial final form level to beat him.