NFE Z Mirror Move Wallbreaker (Murkrow) @ Flyinium Z  
Ability: Prankster
EVs: 252 Atk / 4 Def / 252 Spe  
Jolly Nature  
- Brave Bird  
- Sucker Punch  
- Mirror Move  
- Substitute / Drill Peck / Assurance / Protect
Optional Move(s): 
- Haze
- Heat Wave 
- Hidden Power [Fighting]
- Roost
- Taunt 
- Thunder Wave
- Toxic
Optional Item(s): 
- Eviolite
Optional Ability: 
- N/A
Optional EV/IV(s):  
- 252 Atk / 4 Def / 252 Spe (Adamant) 
- 252 Atk / 4 SpA / 252 Spe (Naive)
Overview: With a good offensive STAB attack combination, good Attack, Speed and priority Sucker Punch, Murkrow is a threatening wallbreaker in the tier. It faces competition as a wallbreaker from other Flying-types such as Staravia and Trumbeak, who boast better coverage and U-turn. Murkrow is also very frail and requires a lot of effort to set up but its bulk is somewhat mitigated by priority Z Mirror Move and how it works. 
Z Mirror Move: Mirror Move's Z Effect gives Murkrow +2 Attack and attacks with the Z move equivalent of the last move the opposing Pokemon used. However, Z Mirror Move fails if the opponent switches, if the opponent used a Z move last or if Murkrow was the last Pokemon to attack. Even if Mirror Move fails, Murkrow still gets the +2 Attack boost. Prankster increases the priority of Z Mirror Move, allowing Murkrow to potentially set up on and kill faster threats depending on what move they last used. Brave Bird hits Fighting- and Grass-types such as Monferno, Roselia, Servine, Machoke, and Gloom for super effective damage and hits most neutral targets hard. If necessary, Flyinium Z Supersonic Skystrike can also be used to turn Brave Bird into a recoil-less nuke, at the expense of setup. Sucker Punch acts as both Murkrow's best Dark-type STAB attack and as useful priority, hitting Psychic-types such as Metang hard while also OHKOing faster threats at +2 such as Electabuzz and Frogadier. Prankster Substitute lets Murkrow avoid Will-O-Wisp from the likes of Haunter, Misdreavus, and Dusclops. Drill Peck acts as a secondary Flying-type STAB attack which does not have recoil, letting Murkrow pick off weakened slower threats without taking chip damage. Assurance acts as secondary Dark-type STAB attack and avoids potential Sucker Punch 50/50s against slower Pokemon carrying Substitute, Will-O-Wisp, or other annoying status moves. Protect protects Murkrow from the opposing Pokemon's attack, which then lets Murkrow Z Mirror Move that attack on the subsequent turn.
Checks and Counters: Bulky Steel-types such as Pawniard and Klang can tank a hit from boosted Murkrow and OHKO or severely damage it in return. Bulky physical walls such as Clefairy, Mareanie, and Togetic can easily tank a Brave Bird from +2 Murkrow and OHKO or Haze it in return. Focus Sash Kadabra can revenge kill Murkrow in exchange for its Focus Sash. Substitute Haunter and Kadabra also have good odds of winning Sucker Punch 50/50s and then revenge-killing it. Murkrow is also susceptible to chip from Stealth Rock and Brave Bird, which makes it difficult for it to effectively clean.