if the radius value is the same for X and Y the sprite will be on a circle of this radius
if the radius values are different the sprite will be on an ellipse
That's the basic formula I used for my menu in cubemaze (see below)
Ok I've been kinda ninja'd on this last one. Shouldn't have taken a shower after opening the topic. well..
For the "Shake many objects but not these ones" it depends
If you don't want your HUD to shake you can put all your HUD elements on a layer with parallaxe 0,0 (will never scroll)
Else you will probably have to shake your layout with a scoll+random(-10,10) and counter shake object you don't want to shake by putting them in the same family and applying the inverse translation.
+on what you want
local number randX = 0
local number randY = 0
local number curScrollX = 0
local number curScrollY = 0
+System: trigger once
// store real position on start of shaking
-> System: set curScrollX to scrollX
-> System: set curScrollY to scrollY
-> NoShakeFamily: set self.realX = self.X
-> NoShakeFamily: set self.realY = self.Y
+System: every tick
-> System: set randX to random(-10,10)
-> System: set randY to random(-10,10)
-> System: set scrollX to curScrollX + randX //Shake
-> System: set scrollY to curScrollY + randY //Shake
-> NoShakeFamily: set X to self.realX - randX //Counter-Shake
-> NoShakeFamily: set Y to self.realY - randX //Counter-Shake