Goku Base (Boo) runs the Gauntlet of Android Bows and Cell.

[SIAD]

I have Goku Base near the level of Cell Semi Perfect (Initial).

 

[SSJ2]

Given the fact that Goten and Trunks are shown to be around Android 18's level, and they are each around Cell Games Goku level, I can't see Goku making it past Imperfect Cell (post-humans) or Android 16. Boo arc Goku was far stronger than his Cell Games self, but there's no reason to think he was out of Cell Games Gohan's league.

 

[GSM123]

Loses to suppressed Mecha Freeza.

 

[Captain Cadaver]

As already said, he can't be leagues above #18's level. He can beat #18 and #17 without much difficulty, though is doing nothing to #16.