541-Titan Slayers [TFG] may be able to accommodate a merger. We currently have 19 members, but have some who would be willing to shuffle around to other alliances in the family to make space for all 12.
From the looks of it, we are fairly similar in terms of rules since we also have FFA wars, though we use best tanks rather than coordinating colors (as that seems to be more effective for us).
We are hitting 14* titans which are a bit stronger than the 9-10* you are used to.
Here is our post:
541-Titan Slayers [TFG] Recruiting/Looking for a Merger-Nov 2024
Feel free to reach out to me here or on line (Line ID: igh13) if you are interested and/or want to know more.