Moves
Focus Blast is used break through many Pokemon that can withstand Thunderbolt or Hidden Power Ice without too much difficulty. It can OHKO Probopass and offensive Golem with its Sturdy broken and 2HKO specially defensive Golem, as well as hitting ZU's many Normal-types super effectively, OHKOing or nearly OHKOing defensive ones such as Lickilicky, Assault Vest Komala, and Vigoroth after a Nasty Plot boost when boosted by Fightinium Z or Life Orb. The ability to break through bulky Normal-types after a Nasty Plot boost makes Raichu very difficult to wall. Hidden Power Ice lets Raichu take out Gabite after a Nasty Plot Boost while hitting various Grass- and Ground-types hard without risking missing Focus Blast. Altaria is also hit much harder by Hidden Power Ice than by Thunderbolt, and it is always OHKOed at +2 after Stealth Rock.
Set Details
Maximum Speed and Special Attack investment with a Timid nature is necessary to outspeed Pokemon like Kadabra and Rapidash while hitting as hard as possible. Lightning Rod is the chosen ability to block Volt Switch and force Pokemon like Electivire and Probopass to predict correctly or risk giving Raichu a Special Attack boost. Fightinium Z is used over other Z-Crystals to give Raichu a 190-Base Power Fighting-type attack with perfect accuracy that can break through the many Normal-types in the tier, as well as taking out bulky Golem and offensive Komala without a boost. Life Orb is a good item choice if Raichu's team already has a Z-Crystal user, because Raichu needs to hit as hard as possible and will often fall to attacks with or without the recoil from Life Orb. Life Orb can let Raichu achieve some KOs it would otherwise miss or require All-Out Pummeling to accomplish, such as against Gourgeist-XL and physically bulky Golem after Stealth Rock with a +2 Hidden Power Ice. Physically bulky Golem only has a 6.3% change to be KOed by a +2 Hidden Power Ice without Life Orb, forcing Raichu to use its Z-Move or risk missing Focus Blast. However, the damage from Life Orb can rack up in combination with entry hazards or status damage to put Raichu in range of even very weak attacks such as Gourgeist's Foul Play and Golem's Sucker Punch. If using Life Orb, change Raichu's HP IVs to 29 to take less recoil.
Usage Tips
Raichu can be used either as a battering ram to break a defensive core early- or mid-game or as a fast sweeper late-game. Try to put Raichu into situations where it will force switches, such as against slower Water- and Flying-types or against passive Pokemon that cannot significantly damage it, so that it can boost with Nasty Plot to break through the opposing team. Switching Raichu in directly will nearly always be hazardous, so when possible, bring Raichu in safely through pivoting moves such as U-turn and Parting Shot or send it in after a teammate has fainted. There may not be very many opportunities to set up with Raichu over the course of a battle, and against some offensive teams, there might not be any. If Raichu doesn't need to break through any walls on the opponent's team, it can still be very useful for its high Speed tier and decently powerful attacks.
This set is very effective versus stall and bulky teams because the only relevant Unaware user in ZU, Pyukumuku, is hit super effectively by Thunderbolt. Lickilicky, the most prominent special wall on stall teams, is always OHKOed by +2 All-Out Pummeling without concerns of missing. However, beware that Lickilicky can sometimes dodge the KO with Protect, as +2 Focus Blast does not always KO after a weakened All-Out Pummeling, and +2 Life Orb-boosted Focus Blast is not a guaranteed OHKO either. A small amount of chip damage on Lickilicky can greatly boost Life Orb Raichu's odds of breaking stall.
Choose All-Out Pummeling's target carefully, but be aware that missing Focus Blast against Komala and Golem will often mean the end of Raichu. A neutral All-Out Pummeling hits significantly harder than a neutral Thunderbolt or a super effective Hidden Power Ice, so using it on a target that is not weak to Fighting can sometimes be advantageous. For example, offensive Silvally-Fighting is never OHKOed by a +2 Thunderbolt without Life Orb but will always be KOed by a boosted All-Out Pummeling. Be aware that without Life Orb, boosted Thunderbolts are not that strong and fail to 2HKO some bulky Pokemon like Muk and Bronzor. While Raichu can block Volt Switch from Electivire, Zebstrika, and Probopass, switching into the wrong move from any of these Pokemon can be the last thing Raichu does in a battle.
Team Options
Raichu appreciates Pokemon that can take physical hits, especially Ground-type attacks and Water-type attacks from Floatzel. Grass-types such as Gourgeist-XL, Servine, and Leafeon resist both those types and can check Choice Scarf Electivire. Ground-immune Pokemon such as Altaria, Swanna, and Bronzor can also switch into Ground-type attacks for Raichu. Raichu also pairs well with other special sweepers that appreciate its ability to weaken or KO special walls, such as Chatot, Swanna, and Kadabra. Swanna and Chatot again cover Raichu's Ground weakness, while Raichu blocks Volt Switches aimed at them. Silvally formes, Probopass, Monferno, and Komala can all use pivoting moves to help circumvent Raichu's frailty and bring it in safely. Silvally-Water in particular can help check Floatzel and Golem while luring Electric attacks for Raichu to switch into. Powerful physical attackers such as Rampardos and Komala can take out special walls for Raichu, allowing it to sweep without needing to find an opportunity to set up a Nasty Plot boost. Memento, dual screens, and Parting Shot from Pokemon such as Misdreavus, Dugtrio, Meowstic, and Silvally can weaken incoming attacks to help Raichu set up.