A few things:
1) You don't have to type out every picturebox like that
2) you don't have to set the Top like that as well

From what you gave me there I'd do something like this:
Code:
Option Strict On
Option Explicit On
Public Class Form1
    'Declare a new instance of the random object here,
    'or declare it here, and set it as a new instance at the form load
    Private r As New Random
    Private hit As Integer = 1
    Private pbList As New List(Of PictureBox)

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        pbList.AddRange({PictureBox2, PictureBox4, PictureBox5, PictureBox6, PictureBox7, PictureBox2, PictureBox8, PictureBox9, PictureBox10})

        Timer1.Start()
    End Sub

    Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
        For Each pb As PictureBox In pbList
            pb.Top += 5

            If pb.Bottom >= Me.Bottom Then
                'Hit the bottom
                pb.Location = New Point(r.Next(0, Me.Width), -r.Next(0, 10))
            ElseIf pb.Bounds.IntersectsWith(picCharmander.Bounds) Then
                'Hit charmander
                hit += 1
                pb.Location = New Point(r.Next(0, Me.Width), -r.Next(0, 10) - Me.Height)
            ElseIf hit = 4 Then
                'end game
                Timer1.Stop()
            End If
        Next
    End Sub

    Private Sub Form1_KeyDown(sender As System.Object, e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
        If e.KeyCode = Keys.Left Then
            picCharmander.Left -= 10
        ElseIf e.KeyCode = Keys.Right Then
            picCharmander.Left += 10
        End If
    End Sub
End Class