Delta Vespiquen (DVespiquen) can be played as multiple roles, just like Charizard. It also has wonderful typing of Fire/Steel that makes it only have 3 weaknesses and 10 resistances. It should be used in UU or below as Heatran outclasses it in OU.
Shift Gear makes it oversped entire non-Mega and unboosted UU in USUM while no UU Mega can OHKO DVespiquen. +1 Flare Blitz heavily damages any Pokemon uninvested in HP or defense. Iron Head can OHKO Mega Aerodactyl and Mega Beedrill. Boosted Iron Head OHKOes Mega Absol. Roost to recover any recoil from Flare Blitz. +1 Wild Charge can be used to 2HKO some water Pokemon like Mega Blastoise or Empoleon. Drill Run can be chosen to dent Fire-type switch-ins. Note that Banded Azumarill Aqua Jet is only deal 99% at most and no Mach Punch can OHKO DVespiquen.
Other option is to use Life Orb to make some 3HKO into 2HKO, but the recoil is too much for DVespiquen to handle.
DVespiquen @ Life Orb
Ability: Speed Boost
EVs: 252 SpA / 4 SpD / 252 Spe
A very straightforward set which emphasizes on dealing immediate damage. Fire Blast for power or Flamethrower for consistency. Flash Cannon is a strong STAB to hit rocks that resist fire. Thunderbolt can be used instead to hit waters like Alomomola. Calm Mind is used on opponent’s switch. Protect can be used to stall for Speed Boost while Substitute can do the same including status protection, but no increased priority and reduces HP. Magnet Rise if your team has no ground immunities or Roost to recover HP.
DVespiquen can also use a bulkier option as it has a decent 70/102/102 defenses. Moveset includes Stealth Rock, Toxic, Protect, Lava Plume, Roost, or Thunder Wave.
Check and Counters
Bulky Waters. Alomomola can withstand any attacks from physical variants and heavily counters it with Rock Helmet and Scald. Swampert and Quagsire counter any vespiquen without Energy Ball.
Fighting types. Special variants are countered by Assault Vest Conkeldurr / Machamp. Physical variants are checked by Fast fighting types such as Mienshao.
Fire types. Drill Run or Earth Power on the switch is needed to stop Darmanitan or Infernape.
Neither of these sets are good at all. UU is infested with bulky Water types which easily eat up even boosted Wild Charge.
+1 252+ Atk Delta Vespiquen Wild Charge vs. 252 HP / 252+ Def Suicune: 180-214 (37.3 - 44.3%) – 100% chance to 3HKO after Leftovers recovery
252+ SpA Life Orb Delta Vespiquen Thunderbolt vs. 252 HP / 4 SpD Suicune: 213-252 (44.1 - 52.2%) – guaranteed 3HKO after Leftovers recovery
+1 252+ Atk Delta Vespiquen Wild Charge vs. 240 HP / 244+ Def Tentacruel: 262-310 (60.7 - 71.9%) – guaranteed 2HKO after Black Sludge recovery (This looks good, but considering the fact that it needs a boost in the first place to even 2HKO a Pokemon with its weaker defense with a decent supereffective move it really isn’t)
252+ SpA Life Orb Delta Vespiquen Thunderbolt vs. 240 HP / 0 SpD Tentacruel: 205-244 (47.5 - 56.6%) – 35.5% chance to 2HKO after Black Sludge recovery
Being able to kill Mega Beedrill and Mega Absol means nothong. They are both extremely frail. Even at +2, it’s still slower than most Scarfers, which means that it isn’t a reliable sweeper at all. Even if it can live hits, it can’t even kill the Scarfers back. You’re better off using Infernape as a setup sweeper because it can also boost in either stat, it can use Swords Dance or Nasty Plot instead of Shift Gear and Calm Mind, it has higher attack stats, and has priority. While Infernape can be walled by some of the same things as D Vespiquen depending on its set, it has the power and coverage to actually deal with those Pokemon. There are far too many good offensive Fire types in UU for D Vespiquen to stand out amongst them as an attacker.
honestly its a great transition pokemon, it has plenty of resistances with steel and fire making it normally effective. If you give it a assault vest and givei t 31 all the way round. 255 in spec def and spec attack and 4 hp you have a monster tank with speed boost
give it charge beam, once you get 1 to 2 raises then you will be steam rolling. you then give it dazeling gleam, thunderbolt or heat wave, if you need swap up one with flash cannon. its well rounded and it a JUGGER!
obviously mischevous or soec def nature and i went with modest for the added power. like i said great for transitioning if they arent a ground type. like good stacking capability with fiary types which are pretty meta at the moment.