Append "Contrôle". au début de la propriété et supprimez le TargetType. Ensuite, dans les styles qui en dérivent, utilisez BasedOn avec une StaticResource pointant sur le style de base.
<Style x:Key="basicStyle">
<Setter Property="Control.FontFamily" Value="Tahoma" />
<Setter Property="Control.FontSize" Value="12" />
</Style>
<Style TargetType="{x:Type Label}" BasedOn="{StaticResource basicStyle}">
<Setter Property="HorizontalAlignment" Value="Right" />
<Setter Property="VerticalAlignment" Value="Center" />
</Style>
<Style TargetType="{x:Type TextBlock}" BasedOn="{StaticResource basicStyle}">
<Setter Property="HorizontalAlignment" Value="Left" />
<Setter Property="VerticalAlignment" Value="Center" />
</Style>
<Style TargetType="{x:Type Button}" BasedOn="{StaticResource basicStyle}">
<Setter Property="HorizontalAlignment" Value="Center" />
<Setter Property="VerticalAlignment" Value="Center" />
<Setter Property="Margin" Value="2,4" />
</Style>