Doing an in-game trade only run of UM and I'm pretty disappointed in Barboach. It's been slightly overleveled due to bonus Exp gain but despite that its performance up through Guzma 1 has been lacking. Should go down from B to C.
I'm using the trade, Babo. You can catch Barboach earlier in Paniola Town but Babo wasn't going to do anything against Araquanid anyway. Haven't used tutors but looking at the list there's not much it looks like it can use. Also no Refresh or Roto Loto.
Barboach can deal decent damage but its health and speed are not great, so there's a number of situations 1v1 where both Barboach and its opponent 2HKO, but Barboach loses because it's slower. Bulldoze in Konikoni kinda helps but by that point you're closing in on Whiscash and then Earthquake.
Fire trial, the trial where you'd most want a Water/Ground Pokémon, isn't great for it. If you run Barboach as your lead, it's liable to damage from the Marowak and Magmar fights, and if that happens, the Totem finishes it with Brick Break before it pulls off an attack. If you bring it in against the Totem after turn 1, it's risking getting downed by Salazzle + Marowak before it can act. Either way, even if it lives, Z-Water Pulse only does around 60%. Magnitude may be stronger but it's not like you can reset easily if it rolls low. It can contribute if you put some levels on it but it can't anchor your team.
Olivia 1 is better for it in that it can beat Lycanroc 1v1 if it either revenge kills or Shift switches in (Anorith does around half with Bug Bite). Either two Bulldozes or Z-Aqua Tail will do it, but again, if it takes two hits it's done, and it will get hit once before it moves. It's possible to have Whiscash for this by doing more optional fights, which could beat both Anorith and Lycanroc, but that's two levels over Lycanroc. (Mine evolved following this fight.)
Its best battle is probably Togedemaru, which it can solo relatively comfortably as Whiscash, though I should note mine picked up Earthquake after beating the preceding Electabuzz. Earthquake 3HKOs Togedemaru, but if you're running Bulldoze or Magnitude this is probably a 4 or 5 hit affair. At least Whiscash has the bulk to shrug off Bounces and Steel Wings from Togedemaru and Skarmory, but it may need a few Potions. The play here might be to keep Mud Bomb around as the fourth move, since even though it's weaker and off a worse base stat it bypasses the Def boost and multitarget penalty.
Guzma 1 wasn't great because this is around when evolved enemies start using good STABs, which counteracts Whiscash's extra bulk. Mine couldn't revenge kill Masquerain (came in without getting Intimidated) because Rock Tomb did about half and the speed drop wasn't enough, so it went down in two hits of Bug Buzz. Considering that there's more Guzmas after this one and Vikavolt has Energy Ball, these seem like a bad time.
Maybe it picks up later but considering that it has its best moves and it's done all its best boss fights other than Hapu and Olivia 2 I'm not optimistic. None of the upcoming trials have Grass moves so it can probably get at least a hit in, but it just doesn't have the stats even evolved to win a majority of neutral matchups 1v1. If I wasn't doing this specific run I would drop it after Togedemaru, but it’s not like Noinoi or Arbo can shoulder the burden.
Barboach can deal decent damage but its health and speed are not great, so there's a number of situations 1v1 where both Barboach and its opponent 2HKO, but Barboach loses because it's slower. Bulldoze in Konikoni kinda helps but by that point you're closing in on Whiscash and then Earthquake.
Fire trial, the trial where you'd most want a Water/Ground Pokémon, isn't great for it. If you run Barboach as your lead, it's liable to damage from the Marowak and Magmar fights, and if that happens, the Totem finishes it with Brick Break before it pulls off an attack. If you bring it in against the Totem after turn 1, it's risking getting downed by Salazzle + Marowak before it can act. Either way, even if it lives, Z-Water Pulse only does around 60%. Magnitude may be stronger but it's not like you can reset easily if it rolls low. It can contribute if you put some levels on it but it can't anchor your team.
Olivia 1 is better for it in that it can beat Lycanroc 1v1 if it either revenge kills or Shift switches in (Anorith does around half with Bug Bite). Either two Bulldozes or Z-Aqua Tail will do it, but again, if it takes two hits it's done, and it will get hit once before it moves. It's possible to have Whiscash for this by doing more optional fights, which could beat both Anorith and Lycanroc, but that's two levels over Lycanroc. (Mine evolved following this fight.)
Its best battle is probably Togedemaru, which it can solo relatively comfortably as Whiscash, though I should note mine picked up Earthquake after beating the preceding Electabuzz. Earthquake 3HKOs Togedemaru, but if you're running Bulldoze or Magnitude this is probably a 4 or 5 hit affair. At least Whiscash has the bulk to shrug off Bounces and Steel Wings from Togedemaru and Skarmory, but it may need a few Potions. The play here might be to keep Mud Bomb around as the fourth move, since even though it's weaker and off a worse base stat it bypasses the Def boost and multitarget penalty.
Guzma 1 wasn't great because this is around when evolved enemies start using good STABs, which counteracts Whiscash's extra bulk. Mine couldn't revenge kill Masquerain (came in without getting Intimidated) because Rock Tomb did about half and the speed drop wasn't enough, so it went down in two hits of Bug Buzz. Considering that there's more Guzmas after this one and Vikavolt has Energy Ball, these seem like a bad time.
Maybe it picks up later but considering that it has its best moves and it's done all its best boss fights other than Hapu and Olivia 2 I'm not optimistic. None of the upcoming trials have Grass moves so it can probably get at least a hit in, but it just doesn't have the stats even evolved to win a majority of neutral matchups 1v1. If I wasn't doing this specific run I would drop it after Togedemaru, but it’s not like Noinoi or Arbo can shoulder the burden.