To gather requirements for implementing an omnichannel solution, I would start by organizing a series of workshops and interviews with key stakeholders from various departments such as sales, marketing, IT, and customer service. This would help me understand their specific needs and expectations. I would also conduct surveys to gather input from end-users and customers to ensure their perspectives are considered. 

Next, I would document the gathered requirements and perform a gap analysis to identify any discrepancies between the current state and the desired omnichannel solution. I would use tools like JIRA or Confluence to maintain a traceability matrix, ensuring all requirements are tracked and aligned with the project goals.

To ensure alignment across teams, I would facilitate regular cross-functional meetings to discuss progress, address any concerns, and make necessary adjustments. I would also create a communication plan to keep all stakeholders informed and engaged throughout the project. By fostering a collaborative environment and maintaining open lines of communication, I would ensure that all teams are aligned and working towards a common goal.