Yes they do get more powerful stats when they evolve, but they learn more powerful moves slower. Your most likely better of evolving them as soon as you can.
Sources:
Personal experience
Pokemon evolve so that you can have a larger variety of Pokemon and to have better ones that can be more powerful.
Evolutions? That means, when a Pokemon levels up to a certain level, it will change into a more powerful and stronger form. The most stages a Pokemon will go through is 3, each getting more powerful. However, some Pokemon do not evolve at all. hope that helped, pickomon
Yes, because it is more powerful when it evolves into a Lucario than just staying a Riolu.
raise it to lv 20 and it will become powerful!
it depends. the higher the level the more powerful it is. if its a high level then it is powerful. evolve it into floatzel. it even more powerful.
a boy kirlia will evolve into gallade with a dawn stone (beware it must be a boy) i have done this and a gardvoir is more powerful than gallade.
There are a bunch of Pokemon that can evolve: Nidoran, Pidgey and plenty more.
Pokemon
He will evolve into Garchomp at level 48. It takes a long time but he has very powerful movies and is really strong.
for Pokemon it means that the Pokemon wasn't completley ready to evolve or you have an ever stone attached to the Pokemon so level the Pokemon up more
There are a few Pokemon that evolve from the safari zone, pikachu, goldeen, psyduck and many more.
This does 2 things; 1, tells you how powerful Return/Frustration is, and 2, some Pokemon evolve through max happiness after you level them up, so it tells you if that Pokemon would evolve.