Web site and application
Don't make your attendees ask which accommodations you're able to provide. Be up front about what you're able to do! This will encourage people who need those accommodations to apply, since they will be confident that they can participate in your event. Being specific with your list of accommodations will show potential attendees that you're working to create a space where access and inclusivity are priorities. You can just add these as questions in your FAQ section. See this event for some suggestions.
Ask for suggestions from your coaches and attendees on other things you might want to provide. For example, maybe you can find a friend to volunteer time for child care.