I have not done something like that before but I imagine the following tag might be useful:
#ZWC# Number of watch face activations since synced eg. 26
You could have 5 layers, one for each gif image.
You could set the opacity on each to:
where you replace X by 0 to 4 for the relevant layer.
Now random, hmm …
I imagine the appropriate expression to use would be
Random number generator that’s updated every time the watch face goes into active mode
eg. (wakeRand(1, 10))
But I can not think of an elegant way of using it to do what you want. A rather crude way of doing it would be to again have 5 layers and set the opacity of top 4 to
where again you replace X with 1…4 for the relevant layers.
And just set the opacity of the bottom gif layer to 100.
Basically, if their number comes up the relevant top four layer(s) will be visible and overwrite the lower layers. If none of their numbers come up they will be hidden and the bottom layer will be visible.
I can’t think of a better, more elegant way of doing it.
I hope that helps.