[FluentValidation.Attributes.Validator(typeof(LeagueValidator))]
public class LeagueViewModel
{
    public string LeagueName { get; set; }
    public DateTime SeasonBeginDate { get; set; }
    public DateTime SeasonEndDate { get; set; }

    public List<TeamViewModel> TeamViewModels { get; set; }
}

public class LeagueValidator : AbstractValidator<LeagueViewModel>
{
    private readonly ILeagueService _leagueService;

    public LeagueValidator(ILeagueService leagueService)
    {
        _leagueService = leagueService;

        RuleFor(x => x.SeasonEndDate)
            .NotNull()
            .GreaterThan(x => x.SeasonBeginDate)
            .WithMessage("Season End Date must be later than Season Begin Date.");
    }
}

public class LeagueValidatorFactory : ValidatorFactoryBase
{
    private readonly Container _container;

    public LeagueValidatorFactory(Container container)
    {
        _container = container;
    }

    public override IValidator CreateInstance(Type validatorType)
    {
        return _container.GetInstance<LeagueValidator>();
    }
}

private static void RegisterValidators(Container container)
{
    DataAnnotationsModelValidatorProvider.AddImplicitRequiredAttributeForValueTypes = false;

    var leagueValidatorProvider =
        new FluentValidationModelValidatorProvider(new LeagueValidatorFactory(container));
    leagueValidatorProvider.AddImplicitRequiredValidator = false;
    ModelValidatorProviders.Providers.Add(leagueValidatorProvider);

    container.Register<LeagueValidator>();
}