To be honest this isn't a great team synergy as your team has a ton of weakness, a ground, dark, and fairy (well that's just for the garchomp but aegislash can help in resisting those types). Since your focused on raichu as your terrain sweeper then that's what will focus on.
1) First change the moveset of tapukoko if you wanna make it live long:
Offensive Piviot:
Tapu Koko @ Heavy-Duty Boots
Ability: Electric Surge
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Thunderbolt
- Dazzling Gleam
- U-turn
- Roost
Explanation: For this tapu koko is reliable for setting up electric terrain, Dazzling Gleam is a good STAB move that does reliable damage, it's also super effective against dragon types like hudreigon latios, latias, etc who resist thunderbolt, U-Turn allows tapu-koko to reliably pivot against ground types such as hippowdon and grass types such as ferrothorn.
Other Options of Movesets: You may replace Dazzling Gleam with Toxic in order to cripple pokemon such as tangrowth, hippowdon, and etc.
2) Next change your raichu's movesets cuz you have a lot of electric STABS so that's won't do, I would highly reccommend this build:
Raichu-Alola @ Life Orb
Ability: Surge Surfer
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Rising Voltage
- Psychic
- Focus Blast
- Nasty Plot
Explanation: Rising Voltage deals great damage to pokemon such as Aegislash, Galarian corsola, etc. Psychic deals grea amount of damage (possibly a OHKO) among posion types such as Amoonguss, Dragalage, Nidoking, Drapion. And hits electric resistant opponent such as dragapult, Thundurus-T, etc. Focus Blast does heavy amount of damage to dark and steel types such as Tyranitar, Ferrothorn, Excadrill, Kyurem. Grass knot is use to hit water types that are immune to Rising Voltage such as Swampert, and Gastrodon (Possibly Seismitoad as well), I chose timid nature as well to outspeed foes as such like Volcarona, Hydreigon, Garchomp, etc outside of electric terrain.
Other Option of Movesets: you can replace grass knot with knock off for removing Items that benefits a foe such as Assault Vest Slowking. Or replace grass knot with Nasty plot to deal higher damage, however you will struggle from pokemon who resist rising voltage.
Additional Information:
-Alolan Raichu is weak to specially defensive walls such as blissey, celebi, and also galarian slowking.
-Alolan Raichu has problems with residual problems: Such as life orb damage, Entry Hazards, and toxic.
-Alolan Raichu is also weak to revenge killers such as Choice Scarf Galarian Darmanitan, Choice Scarf Excadrill, and possibly barraskweda without the presence of electric terrain that's why don't let your tapu die early without these threats being killed.
-Alolan Raichu is finally weak to strong priority users such as Urshifu-Rapid, Crawdaunt, Dragonite, Rillaboom, etc because Alolan Raichu is very frail.
3) Why is there a calm mind calyrex-shadow if your running scarf??? If you wanna run scarf here is a reccomendation for you:
Calyrex-Shadow @ Choice Specs
Ability: As One (Spectrier)
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Astral Barrage
- Psyshock
- Trick
- Aromatherapy
This is the standard Calyrex-S set. Astral Barrage is a very strong move that deals massive damage. So please if you know there are normal type such as blissey or dark type pokemon such as yvetal on your foe's side try to predict what it will do, "will it switch or will it keep going if it switches I'll just switch with a fairy type!", Psyshock deals great damage to blissey, Trick would be your third option to stop blissey's shenanigans and aromatherapy to heal statuses.
4) And please replace your lunala with Necrozma DM:
Necrozma-Dusk Mane @ Rocky Helmet
Ability: Prism Armor
EVs: 252 HP / 136 Def / 120 Spe
Impish Nature
- Stealth Rock
- Moonlight
- Sunsteel Strike
- Toxic/ Thunder wave
Necrozma DM's purpose for your team is to put rocks and distroy focus sashes making it less worrying for raichu to deal with focus sash mons, moonlight for healing you from a ton of damage, sunsteel strike for a additional damage, Toxic or Thunder Wave to either criple pokemons or slow foes.
5) Yveltal @ Life Orb
Ability: Dark Aura
EVs: 4 Atk / 252 SpA / 252 Spe
Hasty Nature
- Oblivion Wing
- Dark Pulse
- Heat Wave
- Sucker Punch
Yvetal is a good pokemon to be a potential wallbreaker and a late game cleaner due to it's STAB and dark aura and coverage options, It's with a solid bulk witch also beats ditto on a 1v1, Oblivion recovers your health and becames Max airstream which gives you speed boost and a massive damage to weakend teams, Dark pulse become Max Darkness under Dynamax, which lowers foes' Special Defense, Heat Wave targets Zacian-C, OHKOing the said foe after some chip damage or if sun has been set by Max Flare, and also OHKOes Ferrothorn.
6) Remove aegislash and put Xerneas on it as a good check to strong dragon type in case your leads get knocked out:
Xerneas @ Power Herb
Ability: Fairy Aura
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
- Geomancy
- Moonblast
- Thunder
- Substitute
Xerneas shapes the metagame around it with its Geomancy set due to a good offensive typing, a potent ability, a wide offensive movepool, and most importantly, the option of breaking through its checks with Dynamax, which grants Xerneas additional bulk and power and an immunity to phazing. Geomancy turns Xerneas into an extremely powerful, fast, and bulky setup sweeper at the cost of its item slot. After Geomancy and the boost from Fairy Aura, Moonblast OHKOes everything that does not resist it apart from Dynamaxed Pokemon and extremely bulky Pokemon such as Chansey and Lunala with its Shadow Shield intact.
That is all hope you like this suggestions, thanks!
