This is all largely irrelevant; you just proved that there is ample counterplay to Barraskewda. You cannot just single it out because it has Flip Turn -- games are all about being able to assess risk, sequence, etc.
You cannot ban something because it being paired with Raging Bolt or Iron Treads is hard for single Pokemon -- users of these Pokemon have their own teammates and cores, too. This is the point of playing the actual game and trying to out-position the opponent to win.
I agree with the fact that you have to assess risk, but something like say, rillaboom, gets 2 hit ko'd by barra liquidation.
252+ Atk Choice Band Barraskewda Liquidation vs. 0 HP / 4 Def Rillaboom in Rain: 179-211 (52.4 - 61.8%) -- 98.8% chance to 2HKO after Grassy Terrain recovery
Dragonite with even a little bit of chip to get rid of multiscale get's 2hit ko'd, and that's the bulky version.
252+ Atk Choice Band Barraskewda Liquidation vs. 144 HP / 0 Def Dragonite in Rain: 172-203 (47.9 - 56.5%) -- 89.1% chance to 2HKO
Raging bolt can get 2hit ko'd by barra liquidation or 2hit ko'd by cc.
252+ Atk Choice Band Barraskewda Liquidation vs. 64 HP / 28 Def Raging Bolt in Rain: 174-204 (42.7 - 50.1%) -- guaranteed 3HKO after Leftovers recovery
252+ Atk Choice Band Barraskewda Close Combat vs. 64 HP / 28 Def Raging Bolt: 217-256 (53.3 - 62.8%) -- guaranteed 2HKO after Leftovers recovery
Archaludon is great against barra, but that just means you have to use the playstyle barra is run on, meaning you are abusing it yourself.
Oh, also gets destroyed by cc, so if they predict, they can take it out.
252+ Atk Choice Band Barraskewda Close Combat vs. 204 HP / 0 Def Archaludon: 330-390 (88.7 - 104.8%) -- 31.3% chance to OHKO
Ogerpon gets destroyed by cc.
252+ Atk Choice Band Barraskewda Close Combat vs. 0 HP / 0 Def Ogerpon: 239-282 (79.4 - 93.6%) -- guaranteed 2HKO
Walking wake gets destroyed by cc, nothing new.
252+ Atk Choice Band Barraskewda Close Combat vs. 12 HP / 0 Def Walking Wake: 224-264 (65.4 - 77.1%) -- guaranteed 2HKO
Hydrapple can sometimes barely not get 2hit ko'd by cc, but only sometimes.
252+ Atk Choice Band Barraskewda Close Combat vs. 248 HP / 0 Def Hydrapple: 191-225 (46 - 54.2%) -- 54.3% chance to 2HKO
Sinsticha counters barra extremely hard, but if you are having to run sinistcha, that isn't a good sign. It's a good mon, but shouldn't be required to deal with barra.
Dondozo should never be used to say something is wallable, it is run on stall teams mainly, and can struggle with other mons.
Every counter to barra except for sinistcha, dondozo and potentially Hydrapple and Dragonite, can be either beaten with sheer power or predicts.