For everyone struggling to complete all the missions, you can use these 2 decks:
1. Life cost 0 Stein deck: when your LP is less than 1000 (but more than 200, to survive against D.D. Miasma)
Put healers such as Hummingbird and Pikeru.
2. Yubel deck: use when your LP is higher than 1000. LP Boost α helps a lot.
Extra Deck: Ojama King and Gatling Dragon.
The ideal starting hand would be Cyber Stein and any healer. Getting 1st turn is more preferable since you can lock your opponent's monster zone.
Summon Gatling Dragon if you got 2nd and your opponent already summoned monster(s).
Put some tech cards to counter particular decks, e.g Debunk to negate Fabled Catsith's effect