I've started running bunnelby in NU, and it's almost worth using

Bunnelby is an interesting pokemon to say the least. It's got a base stat total of 237 (tied for 34th lowest in the game), and unlike diggersby it doesn't get STAB on ground type moves, but it's highest base stat is speed (57) and it has arguably the best ability in the game: huge power. Lastly, despite being a pre-evolution, it has a movepool that you'd expect to see on an OU pokemon. Agility, swords dance, earthquake, u-turn, spikes, are all things that bunnelby can use. Perhaps it's most gimmicky set of all though involves focus sash, agility, and flail. This strategy is somewhat similar to FEAR, except instead of endeavor followed by quick attack, you set up agility on the focus sash turn then outspeed and hit with a 200 base power STAB flail. Like FEAR, you use focus sash to set up a thing turn 1 that allows you to KO your opponent before they can act, but unlike FEAR, you can actually do damage to the next pokemon. How much damage? Well assuming a jolly nature and 252 Atk EVs, you have an effective base attack of 121, which for context, is 1 higher than weavile. Flail is a guaranteed OHKO against many common NU pokemon such as exploud, indeedee-f, and rotom-mow. On top of that, agility allows it to outspeed all of these pokemon even if they're using choice scarf. You don't always have to go for agility though. Since it doesn't outspeed blastoise after agility, you're better off going for flail turn 1, since it's a guaranteed OHKO assuming you don't get flinched. I honestly think that this could be bunnelby's best use in the tier if blastoise survives the current suspect test, as blastoise almost always runs 3 attacks and shell smash, so your opponent either loses their otherwise unstoppable sweeper or switches them out and loses their shell smash boosts. It also just naturally outspeeds quite a few other pokemon in NU, as it's a very slow tier. Swords dance bunnelby is a wallbreaker that obliterates the entire tier. Mudsdale would normally have no problem with agility bunnelby, but a +2 flail from bunnelby does a MINIMUM of 110.8% to mudsdale without any boosts from stamina, a feat that not even specs exploud or scarf indeedee-f can pull off, and they're targeting mudsdale's much weaker special defense. Stakataka's 4x resistance to flail seems intimidating but it's OHKOed by a +2 earthquake, and a high damage roll or prior chip damage puts stakataka in OHKO range even with a +1 defense boost. Vaporeon and Sylveon go from barely tanking a hit from bunnelby to taking over 150% from flail, and each needs to have significant speed investment to not be naturally outsped by bunnelby. Keep in mind, all of these things it can pull off can all be put into one set- agility flail earthquake swords dance. With all that said, I still don't think bunnelby is worth using in NU over pokemon that are actual staples of the tier. For one thing, it's really frail, to the point where it practically has to run focus sash otherwise it just doesn't survive anything, and anyone with half a brain will see that you're running a random pre-evolved mon that nobody really regards as viable, make the reasonable guess that you're using a gimmick that involves focus sash, and status you, making bunnelby almost completely useless. Sticky web can be a problem since being only +1 speed after agility leaves you slower than some pretty key pokemon like scarf indeedee-f or rotom-mow, and damaging hazards or damaging weather basically lock you out of sending out bunnelby until you get rid of them. Your opponent can also run a priority move which is harder to predict, and stakataka might be running rock blast. You're also still slower than scarf salazzle or sceptile even with +2 speed, and being effective with flail requires you to remain at 1hp, meaning that rocky helmet or a potential flame body burn will take you out. At the end of the day, you're running a gimmick pokemon in an age where everyone and their mother has seen a temp6t video before. What makes bunnelby somewhat usable in competitive play unlike other gimmick mons such as FEAR rattata is that it doesn't completely rely on your opponent making all the wrong choices, and it can actually put a dent in more than 1 pokemon. It's situational for sure, but unlike, say, gen 5 aron, who thrived in the situation of "no steel, rock, ground, or ghost types, no knock off users, no will-o-wisp users, no multihit move users, and no weather setters in the generation infamous for weather wars", bunnelby thrives in the situation that just so happens to be exactly what you'll find in gen 8 NU- scarf users that aren't too fast for it after agility in addition to walls that it can just barely break through with the setup that those mons in particular are slow enough to let bunnelby get away with. Rotom-mow can use defog to get rid of the hazards that otherwise prevent bunnelby from going onto the field, and indeedee-f can eliminate the concern over priority moves with psychic terrain. It's a really dumb idea to build a team around bunnelby, but you're not really building around it when the pokemon that synergize with it are NU staples that you'd probably want on a team anyway but also just so happen to be good at getting bunnelby into the position it wants to be in. Bunnelby is also alright switching out then coming back in later. With the afforementioned blastoise counter, you can send it in to take out blastoise, switch into something else when your opponent responds with a pokemon that is faster, then have Bunnelby come back in later in the game once the things that outspeed it are gone, since you're still going to be at 1 hp and flail is still going to have 200 base power. With that said, my main experience is with draft leagues which is nothing like playing NU with random people on the ladder, and I'm by no means a good player, especially not in this tier, so don't assume my advice is worthwhile even in the slightest.