[CmdletBinding()]
Param(
    [Alias('Boss')]
    [Parameter(Mandatory,Position=0)]
    [Microsoft.ActiveDirectory.Management.ADUser]$Manager,

    [Alias('User')]
    [Parameter(Mandatory,Position=1)]
    [Microsoft.ActiveDirectory.Management.ADUser]$Employee,

    [Alias('ID','TrackingNo','Reference')]
    [Parameter(Mandatory,Position=2)]
    [uint32]$TrackingNumber,

    [Alias('Workstation','Machine','Computer')]
    [Parameter(Mandatory,Position=3)]
    [string]$ComputerName,

    [Alias('TicketID','TicketReference','Ticket')]
    [Parameter(Mandatory,Position=4)]
    [uint32]$TicketNumber,

    [Alias('NewEmail','CreateEmailAddress')]
    [Parameter(Mandatory,Position=5,ParameterSetName='NewHire')]
    [System.Net.Mail.MailAddress]$NewHireEmail,

    [Alias('InitializationText')]
    [Parameter(Position=6,ParameterSetName='NewHire')]
    [string]$NewHireText = "Default new hire text here.",

    [Alias('NewHirePassword','UserPassword')]
    [Parameter(Position=7,ParameterSetName='NewHire')]
    [securestring]$Password = (Read-Host -Prompt "Enter initial password for user:" -AsSecureString),

    [Alias('VanillaImage','VanillaImg','BaseImg')]
    [Parameter(Mandatory,Position=5,ParameterSetName='BaseMigration')]
    # Replace this type with appropriate type for whatever your input is supposed to be here
    [PsObject]$BaseImage,

    [Alias('MoveEmail','MigrateEmail','MoveAddress','MigrateAddress')]
    [Parameter(Mandatory,Position=6,ParameterSetName='BaseMigration')]
    [System.Net.Mail.MailAddress]$MigrationEmailAddress,

    [Alias('MigrateText')]
    [Parameter(Position=7,ParameterSetName='BaseMigration')]
    [string]$MigrationText = "Default migration text here.",

    [Alias('CannedResponse')]
    [Parameter(Position=8,ParameterSetName='NewHire')]
    [Parameter(Position=8,ParameterSetName='BaseMigration')]
    [string]$AutoReply = "Default autoreply text here."
)
Begin {
    function Complete-AssetDeployment {
        [CmdletBinding()]
        Param(
            # ???
        )
        # No idea what you're trying to do with this one yet. Try to define it more clearly.
    }

    <#
        This one's also up to you, as the specifics depend heavily on your environment.
        The relevant help file(s) can be found here:
        https://technet.microsoft.com/en-us/library/aa998225(v=exchg.160).aspx

        Specifically, you'll need to connect to a mailbox and use New-MailMessage
        to create the email. Suggested script parameters are listed below.
    #>
    function New-AutomatedMailMessage {
        [CmdletBinding()]
        Param(
            [Alias('To')]
            [Parameter(Mandatory,Position=0)]
            [ValidateNotNullOrEmpty()]
            [System.Net.Mail.MailAddress[]]$Recipients,

            [Alias('Cc')]
            [Parameter(Position=1)]
            [System.Net.Mail.MailAddress[]]$CarbonCopies,

            [Alias('Bcc')]
            [Parameter(Position=2)]
            [System.Net.Mail.MailAddress[]]$BlindCarbonCopies,

            [Parameter(Position=3)]
            [string]$Subject,

            [Alias('Message')]
            [Parameter(Mandatory,Position=4)]
            [string]$Body
        )
        # Function body goes here.
    }

    function Reset-ADUserPassword {
        [CmdletBinding()]
        Param(
            [Alias('Username','SamAccountName','Name')]
            [Parameter(Mandatory,Position=0,ValueFromPipeline)]
            [string]$Identity,

            [Alias('NewPassword')]
            [Parameter(Position=1)]
            [securestring]$Password = (Read-Host -Prompt "Enter initial password for user:" -AsSecureString),

            [Parameter(Position=2)]
            [switch]$ChangeAtLogon
        )
        Set-ADAccountPassword -Identity $Identity -Reset -NewPassword $Password
        Set-ADUser -Identity $Identity -ChangePasswordAtLogon ([bool]$ChangeAtLogon)
    }
}
Process {
    switch ($PSCmdlet.ParameterSetName) {
        'NewHire' {
            Write-Verbose "Performing New Hire functionality."
            # Call appropriate functions with appropriate parameters and do whatever else you need to here
        }
        'BaseMigration' {
            Write-Verbose "Performing Base Migration functionality."
            # Same here, for the other purpose of the script
        }
    }
}
End {
    <#
        This section is for cleanup. Any remaining open connections, mailboxes, sockets, streams, etc.,
        that need to be tidied up should be taken care of here and properly disposed of.
    #>
}