Hmm lugia is not the best choice but should be possible.
LVL 30 Mewtu destroy Gengar with a huge time difference, you should power up some and use them first.
https://www.pokebattler.com/raids/defenders/GENGAR/levels/RAID_LEVEL_3/attackers/levels/30/strategies/CINEMATIC_ATTACK_WHEN_POSSIBLE/DEFENSE_RANDOM_MC?sort=TIME&weatherCondition=NO_WEATHER&dodgeStrategy=DODGE_REACTION_TIME&aggregation=AVERAGE&randomAssistants=-1
gengar solo 3*
as sad as it is i didnt manage to solo gengar yeterday i solod a hard raid boss tangela wiht out of breaking a sweat but gengar 4 tries and i kept loosing by the clock so should i use my lvl 31,5 lugia with boht psycic type moves for not fainting out i have only 1 tytar and 1 groundon both very high lvl 1 SB mewtwo also strong lvl (and Lucky not that it matters i just say it) but i just come short on bulk. (tangela solo guide moltres sky attack all you need to know)
Answers
While most people in my area struggle against Sludge Bomb (cloudy is really common), I have a much easier time with it than Shadow Ball. I use a lot of Gengar itself, SB Mewtwo and the 3 big psychics (Mewtwo, Alakazam and Espeon), that's the reason. Their 1-bar charge moves end up being ridiculously slow in the end if I get 1-hit-KO'd.
Against ShB Gengar you can try with other slower but less frail options like Tyranitar and Houndoom, especially now that weather boosted Houndour are common sights. Never underestimate Foul Play + resistances in spite of lower overall stats.
I personally don’t have any problem with Gengar. I already made 3 of them. (2 Shadow Ball, 1 Sludge Bomb). I post my team but i guess my Mewtwo gives a lot in this fight, but when i fight SB i need to dodge every charge move from boss. Metagross is my Anchor and he is used at last 5-10% of Gengar’s HP bar. All Mons have their optimal Movesets for this fight.
I got a Sludge Bomb on Cloudy three days ago.
Mewtwo lvl27 10 12 15 C/P
Espeon lvl34 14 12 12 C/FS
Houndoom lvl 31 11 6 13 S/F
Alakazam lvl 32 14 11 10 Pc/FS
Tyranitar lvl 30 15 14 11 B/SE
Rhydon lvl 31 15 10 11 Ms/Eq
Tried 3 times, dodging was my biggest problem there.
I always go to Pokebattler before getting to raid, u should try..