This mon is already one of my favorite Pokemon in this meta due to its sheer versatility while not being overtuned (unlike say Dudunsparce). The movepool this Pokemon has gives it the capability to fulfill a role that your team could want.
Bombirdier @ Choice Scarf
Ability: Rocky Payload / Big Pecks
Tera Type: Flying / Dark
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Knock Off
- Brave Bird
- U-turn
- Stone Edge / Sucker Punch
Probably one of the first sets people gravitate towards when discussing Bombirdier, having the speed to outrun & revenge kill Passimian while still maintaining the ability to U-turn on top of having pretty spammable dual STABs are already the hallmarks of a top tier Scarfer for NU. Rocky Payload Rock STAB adds yet another move for Bombird to be able to throw out, but in practice I never actually clicked it all that much when Bombird's other attacks are so much safer to click. In fact, a move I actually consider having more often is
Sucker Punch, which might sound counterintuitive on a Choice Scarf set of all things, but actually still has value in sniping multiple threats that may still outrun it, be it Lycanroc Accelerock / Bruxish & Basculin Aqua Jet, boosted mons like Oricorios / Unburden Drifblim, faster Scarfers like Rotom / Sawsbuck, etc. This is especially potent on opponents who are aware that you're Scarfed but do not expect still needing to deal with the threat of STAB Sucker Punch, which I personally appreciate more than having Rock STAB. Flying Tera is typically preferred to allow for easier cleanups with Brave Bird, but Dark Tera is perfectly acceptable to both have non-recoil boosted STAB and remove the Stealth Rock weakness.
Bombirdier @ Heavy-Duty Boots
Ability: Big Pecks
Tera Type: Flying
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Knock Off
- Brave Bird
- U-turn / Stealth Rock / Parting Shot / Taunt
- Sucker Punch / Roost
Non-choiced Bombird aims to take maximum advantage of its Knock Offs, especially against switch-ins; Knock + BB does massive chunks of damage, Knock + Sucker puts heavy pressure on faster checks, while Knock + U-turn does solid chip against defensive switch-ins. Flying Tera is much preferred here as HDB means not having to deal with the SR weakness anyway, and Knock into Tera Brave Bird is quite brutal to stomach. With that said, if you do not find yourself needing all of these moves, the beauty of Bombirdier is that it has multiple options to consider. Bombird makes for a very competent offensive Stealth Rocker since it threatens literally all the hazard removers. Roost is a nice option just for longevity. Taunt comboes well with Knock Off to pressure defensive mons, and especially more so if you have U-turn / Roost. Even Parting Shot can be considered for an alternative pivoting move. The sheer amount of options that Bombirdier has at its disposal is staggering, and is extremely customizable as a result.
Bombirdier @ Focus Sash
Ability: Rocky Payload / Big Pecks
Tera Type: Ground
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Stealth Rock
- Taunt
- Memento
- Rock Tomb / Knock Off
I mentioned offhandedly that Bombird can threaten nearly all of the hazard removers; this set fully capitalizes on that aspect to become one of the better suicide leads in the meta. Stealth Rock, Taunt, and Memento are all amazing for giving your team a head start. I honestly prefer Rock Tomb on this set since the speed drop essentially gives Bombird an "extra turn" against faster opponents to do what it needs to, especially against faster Taunt users, but Knock Off can be used as the "default safe STAB" if you choose. The Tera type isn't particularly important for a suicide lead, but if you must, I'd probably recommend Tera Ground to flip the matchup against lead Lycanrocs as well as block Volt Switch, which is otherwise an annoying way for the opponent to break Bombird's Sash / KO it without having to deal with Bombird's Rock Tomb speed drop.
Bombirdier's extensive movepool means there are still other potential sets that it can try to use, like "Hone Claws + Power Trip" or a bulky Bombird variant with moves like Whirlwind and Foul Play. While I don't think these sets are particularly fitting for this current meta, they're still sets to keep in mind. Bombird is deceptively versatile and it'd likely be able to offer something for your team.