Like in the rest of Pokemon videogames, it shakes 3 times when you catch it. Each throw has its chance. If yu throw, and 2 shakes occur and the pokemon scape, next time you can catch it, or maybe 1 shake and scape this time.

I don't consider any useful information about it at all.

Like in the rest of Pokemon video games, it shakes up to 3 times when you catch it.

Each throw has an individual chance. If you throw and 2 shakes occur but the Pokemon escapes, that has no effect on your next throw -- you might catch it, or it might shake once and escape.

In other words, I don't consider you to gain any useful information about it at all.