At the moment I would argue that the situation of the sins vs the commandments (safe for escanor and mel) is that they are all helpless and worthless fodder unable to do a thing to them. And that includes ban and considers how he performed against galan.
first is gowther. Gowther has a convenient technique which works even regardless of power. However in context he still would never win against a commandment. His basic memory wiping does not last to long and would not kill a commandment. Nightmare teller would perhaps be interesting but whether gowther gets to use it depends entirely and exclusively on luck rather than skill. With his current PL absolutely everything gowther does would by all intents and purposes be slow motion against a commandment. Heck, he probably would even blink in slow motion as far as the commandments are concerned. It's not like when he went up against dreyfus. dreyfus was merely comparable to GHKs, his power is not the sort that can immediately obliterate a sin. On the other hand the weakened commandments do have the power to obliterate out of existence with absolute ease at least stuff beneath the 15k range. So assuming gowther tries something like was he did against dreyfus with a commandment it is 99% certain that gowther is obliterated on the spot. His only chance would be that his commandment enemy was either not thorough or by some miracle there was something left of gowther. It'd be interesting if nightmare teller could be used to prey on the commandments own precepts though.
merlin has a number of tricks but realistically speaking nothing she has, at her current pl, can ever work. Gallan or the other commandments could be black out drunk and passed out allowing merlin to simply loose her shit and hit them with absolutely every spell on her arsenal and even then she probably would not even wake up the weakened commandments. Well, maybe the ones that seem to focus on magic and thus have been hit hardest by not having any magic in them would take some damage. But even that is a insane stretch. As far as we have seen the commandments seem to have power upward of 30k at least. So a commandment could have, say, 5000 strength points and it would still be their weakest stat. However that number, worthless to a commandment, would still be more than what merlin or diane could hope to hurt. Maybe if merlin has some spell which works regardless of strength. Something like poison or something... Then she could do something to a hypethetically blackout drunk and passed out commandment. Diane focuses entirely on raw power so she is pretty much screwed here.
King is an interesting case. His standard techniques would in fact not work at all however his actual skillset is the widest among the sins considering the sheer scope of his natural ability and that he combines it with the sacred tree. However even then I don't think he'd be able to do much, at best he'd do marginally better than merlin or diane. His status promotion would actually be able to do something here however there is a crucial flaw to consider. for status promotion to do... something, anything at all, king needs to be able to at least scratch galan. Or do something to galan which he can then promote.His best bet would be that galan gets and actual scratch from king's true chastiefol however king would still be unable to fight after that. And his odds are terrible considering mel's power of darkness, which was actually comparable to what king is able to achieve with true chastiefol, did not manage the necessary scratch.
Ban is the only sin that could, thanks to his ability put up a fight against a commandment, provided the enemy's focus is not magic rather than physical strength. Now, we did see how ban did against gallan and I would argue that his performance there pretty much conclusively proves ban can never hope to win against a commandment. His time limit is too short and he barely managed something against galan. What could perhaps turn the tide is ban getting his sacred treasure though that would still not be enough IMO. Even then, at best it would give him a chance against weakened commandments. However it would not help him against commandments at their power power. Even merascyla thought galan would be able to do better against meliodas had he had magic power. And merascylla genuinely believes that to be a fact because otherwise she would have turned to stone.
