Thank you all so much for your suggestions how to wing against Cauldron dragon! I tried Rainbow Sentinel and it won bbB!
1. Turtle 1 < Atlas 10 Bb
2. Love 1 < Aether 11 bmB
3. Peacock 1 < Watermelon 11 mB
4. Sterling silver 2 < Gold 10 mBb
5. Hypnotic 3 < Rainbow Sentinel 11 B (lost Warrior Princess 13)
6. Turquoise 3 < Aether 11 B
7. Mask 3 < Bride of Franken 9 B
8. Leviathan 5 < Clown 10 B
9. Rose 6 < Sparkler 10 bmB
10. Medusa 6 < Warrior Princess 13 Mmm
11. Brazil 6 < Warrior Princess 13 B
12. Marble 8 < Atlantis 10 bmB
13. Psychedelic 8 < Watermelon 11 M
14. Hibiscus 9 < Autumn 10 mbM (lost Watermelon 11, Warrior Princess 13)
15. Nouveau 12 < Splatter 13 B
16. Trickster 9 < Watermelon 11 bmM
17. Deep Dragon 9 < Lollipop 10 Bb
18. Coral Dragon 9 < Lollipop 10 bM
19. Eclipse 12 < Aether 11 mbM (lost Hypnotic 9)
20. Rogue 14 < Diamond 15 B
21. Serpent 12 < Chrome 10 B
22. Sweet Tooth Dragon 14 < Warrior Princess 13 mbM
23. Cupcake Dragon 16 < Warrior Princess 13 bmM
24. Poison Ivy Dragon 17 < Sparkler 10 mB (lost Comic 10)
25. Kung-Fu Dragon 19 < Idol 10 B (lost Lotus 10, Warrior Princess 13, Spooky Tree 9)
26. Sugar plum 18 < Watermelon 11 mbM
27. Iris 18 < Warrior Princess 13 mbM (lost Atlas 10)
28. Cauldron 20 < Rainbow Sentinel 11 bbB (lost Ghost Armor 10, Warrior Princess 13, Skeletal Knight 6, Moon 3)
29. Unicorn Dragon 20 < Diamond 15 B
30. Venomous Dragon 20 <