Yeah, he did a bit of training because what else does he do besides chase tail and play baseball, but I don't think he was ever shown to make substantial progress, i.e. he didn't gain any new feats or even concrete statements by other characters testifying to being at least as strong as X.

I'm not convinced he could blow up the moon during the Saiyan Saga, but he surely can by Super just through sheer inflation. There is also the increasing aspect of the writers saying "fuck it" and giving characters power-ups that make literally no sense, with the recent Gohan one being the most absurdly egregious offender, so I'm sure that Yamcha could get to one-shotting-planets and well beyond in a single evening if it was more convenient for the plot (it just never will be because Yamcha is irrelevant), or just wish for it on the Dragon Balls and thereby get stronger than Golden Frieza, which apparently is a thing people can just do if the Dragon likes you enough to not have your wish kill you.