Sequence trick
Update: in recent versions Sequence
is specifically handled meaning it cannot be used for this "trick" -- however the mechanism is still valid and alternatives can be used.
As detailed in Plot draws list of curves in same color when not using Evaluate
if items are initially contained in a Head besides List
they are seen as one expression by the style mechanism; if that head later vanishes, allowing it to plot normally, the style remains.
Plot[{1, ## &[2, 3], 4}, {x, 0, 1},
PlotRange -> {0, 5},
PlotStyle -> Thick
]

I illustrated grouping two lines into the same style to show the flexibility of this method but you could just as easily group all the lines as one:
Plot[{## &[1, 2, 3, 4]}, {x, 0, 1},
PlotRange -> {0, 5},
PlotStyle -> Thick
]

I don't know how many other plot types this applies to but it does include ParametricPlot
:
ParametricPlot[
{{2 Cos[t], 2 Sin[t]},
## &[{2 Cos[t], Sin[t]}, {Cos[t], 2 Sin[t]}],
{Cos[t], Sin[t]}},
{t, 0, 2 Pi},
PlotStyle -> Thick
]

Option selector
I suspect your aversion to specifying a PlotStyle
has to do with remembering the default values for the different plot types. If this is the case I suggest that you use a method to fill in these values automatically. For each individual plot type you could define behavior for using PlotStyle -> "Uniform"
as I did for FillingStyle -> "Match"
(S.O.8569242). Or you could use a framework such as the one Leonid laid out in (22697), but I believe you will still have to deal with multiple configurations because e.g. setting PlotMarkers
for ListPlot
will cause all plots to have plot markers (by default) when they did not before.
An alternative to an option selector would be to craft a function that works with the output of each type of plot function to remove styling after-the-fact. This is probably a less ideal way to go but it may still have application.
Here is a working implementation of the first proposed method (from my Stack Overflow post):
Unprotect[Plot, ListPlot, ListLinePlot];
(#[a__, b : OptionsPattern[]] :=
Block[{$psUni = True},
With[{val = ColorData[1, 1]}, #[a, PlotStyle -> val, b]]] /; ! TrueQ[$psUni] /;
OptionValue[PlotStyle] === "Uniform") & /@ {Plot, ListPlot, ListLinePlot};
(#[a__, b : OptionsPattern[]] :=
Block[{$pmUni = True},
With[{val = System`Private`$PlotMarkers[[1]]}, #[a, PlotMarkers -> val, b]]] /; !
TrueQ[$pmUni] /; OptionValue[PlotMarkers] === "Uniform") & /@ {ListPlot,
ListLinePlot};
Now:
data = Table[{k, PDF[BinomialDistribution[50, p], k]}, {p, {0.3, 0.5, 0.8}}, {k, 0, 50}];
ListLinePlot[data, PlotStyle -> "Uniform", PlotMarkers -> "Uniform"]
