The achievement will still unlock if Big the Jonathan is KO'd at Chapter 50.
Since you need to deal little damage while surviving extreme amounts of damage from Big the Jonathan each chapter, the Guardian and Support roles, as well as defensive and healing cards, are strongly recommended. For example, a team of 4 Kyokos all using the Guardian role can tank his damage extremely effectively.
If the Joker mixer is active, it is easily achievable with at least 2 Dealers and 1 Support. Aru is recommended as Dealer since she can supply cards to herself and her teammates using Present for You (Co-op). Cuties is also recommended, as their Hyper Special Stage protects from triggering Boss panels and from being targeted by Mega Rush. Halena is also viable as a Dealer, as her Hyper Safe Journey can protect from Big the Jonathan's numerous out-of-battle damage cards. Chicken is recommended as Support due to its low REC and can quickly generate stars using Golden Egg (Co-op). Shifu Robot is also recommended as Support due to its auto-revive and self-healing passives. The Flipped mixer can also be helpful, since it greatly reduces Big the Jonathan's combat efficiency by inverting his ATK every 3 chapters.
Mix Phenomenon is a very strong card, especially when nearly all the panels are turned into Boss panels. It does not prevent direct engagement like Serene Hush does, but it is almost guaranteed to deny combats from Boss panels.
Metallic Monocoque is also a good card as Big the Jonathan has many cards that deal out-of-battle damage. With multiple copies in hand, one can be virtually immune to the boss's out-of-battle damage. For such strategy to be efficient, the team must find a way to maintain their star count as the effect will not take place if the team cannot afford it, and it might prevent Supports from reviving others when necessary.
Overtime is a very powerful card for both the Dealer and Support. Dealer can use it especially in the late game to skip a turn, while Support can use it to revive players who are far away.
Extend is a must, especially during late games where KOs are generally hard to avoid.
Nice Present allows more card drawing, it should always be in the deck as it does not consume deck points. Passionate Research can help, but overall Dealers can do the job well, therefore you may want to save the deck points for something else.
Mimic can be used to copy helpful Hypers such as Special Stage or Present for You, and possibly proceed to deal out the copied Hyper to other players. Do note that you can't select yourself to be a target of Mimic.
Princess's Privilege can be included if there is the situation where you want to ditch your current hand for better cards.
Holy Night and Piggy Bank are all helpful for maintaining a constant star income, which will be useful for reviving and some other expensive cards like Special Stage at level 4 and above. This, combined with Cuties' and/or Arthur's passive star generation, can increase the start-off-chapter bonus significantly.