How am I supposed to get 2*, 3*, 4* Zemo for the Carina Challenge?

I have a beautiful 6r5 Zemo sig 200 ascended waiting for this challenge for a while, but I can't put a hand on lower version of Zemo for the synergy
And watching videos on Youtube of this challenge it seems very important. For exemple Nagase did it with a 6r4 full synergy and his bleeds are much much stronger than my 6r5, which impact a lot the difficulty of the challenge.
As an endgame player, there isn't much way to get 2*,3*,4* shards and even if I would spare a huge amount of time and energy to do lower level of SQ I should be extremely lucky to pick Zemo out of 250+ champions.
So my feedback is that I think there should be a Zemo selector constantly or periodically available in the shop. HELP!

As an endgame player, there isn't much way to get 2*,3*,4* shards and even if I would spare a huge amount of time and energy to do lower level of SQ I should be extremely lucky to pick Zemo out of 250+ champions.
So my feedback is that I think there should be a Zemo selector constantly or periodically available in the shop. HELP!

2
Comments
3 star will be a bit harder to obtain for you now. There was luck or arena.
I didn't think about the Avenger challenge thanks! Not the challenge I'm looking forward the most tho tbh because it requires ranking-up champions I don't really use. but well I will have to do it eventually so let's consider I have one out of the 3 I'm looking for now.
But 4* Dual Crystals throw me back to my issue of having very few 4* shards every month, and it's still very RNG dependent given the amount of Skill/Mutant champions in the game now.
And 3* shards is even worst.
also compulsive completionist... o_0