No, you can't physically go to the ladder and view the person's full team, because then everyone would steal it and use it themselves.
However, it's still possible to see what many players tend to use in OU. This is thanks to sweepercalc, which keeps usage stats on stuff in Pokemon Showdown. It has stats on the most popular Pokemon, what percentage of teams include it, what moves it often has, its team mates, etc.
If you're looking to get good at competitive, just remember practise makes perfect. It's cliché, but it's true. You have to learn things like prediction and teambuilding yourself, looking at numbers won't make you any better at that.
