SVG animation delay on each repetition

Answer 1

Here's a more elaborated version of Danjiro Daiwa's example without the hidden rectangle to synchronise the animation and without resorting to setting the orange circles out of the visible area to hide them, using opacity="0" instead. There are four animation running at the same time, a1/a2 for the movement, o1/o2 to hide the orange doppelganger circles when they're moving behind/over the blue circle, r1-r4 to change the radius r and f1-f4 to change fill colour.