Homology
Why would a creator make it so that all animals have things in common? How come some species look almost exactly the same? This according to the theory of evolution is because they are closely related, if you look at the limbs of a pterosaur, bird, whale, human, bat, or anything else they are just a change in the shape of this bone and a lengthening of that finger away from being exactly the same as any of the other animal limbs:
The Fossil Record
The fossil record is unfortunately very poor, but there is still signs of evolution. We have found Fossilized Transitional Fossils between most major lineages including Reptile to Bird which includes:
Archaeopteryx
Micro-raptor
Sinosauropteryx
These are just a few of the fossils in this area. There is a lot of other fossils for other intermediate chains including the fish to tetrapod transition:
Acanthostega
Tiktaalik
Ichythostega
There is others too for other transitions and intermediates that can be found in more detail at the intermediate forms list at talk.origins.
The Fact that fossils actually exist is evidence for evolution because a young earth wouldn't have enough time for fossils to form.
Unity of life and Nested Hierarchies
Why would a creator make anything look alike? How come no bats have feathers? A creator could have done that, but why can we classify things, the evolutionary perspective can say it is because if they have recent ancestors they share more traits. Why didn't an all mighty creator put a octopussycat somewhere or a mermaid or a hippocampus( greek legendary fish-horse hybrid), the reason if you accept evolution is because that couldn't evolve with functional intermediate steps.
Ontogeny
Though few humans have a tail at birth all humans have a tail during development. Another example is we go through a three kidneys in development the first is a jawless fish-like kidney and a Reptile-like kidney.
Imperfection, Unintelligent Design and Sub-optimality
Perfection is the mark of a creator, imperfection is the mark of evolution. Some examples include Blind spots, the respiratory system crossing the gastrointestinal system( causing choking) and other problems such as the laryngeal nerve.
Gene Homology
Gene comparisons compare different genes to see how they're similar and if evolution is correct, things probably more closely related will have genomes with less differences in the genes.
Pseudogenes or Junk DNA
99% of the human genome is made of DNA that has no use this is called Junk DNA or Pseudogenes, why would a creator put so much useless stuff in there, that will just use up energy to replicate all the extra DNA, including a gene that is used to produce artificial vitamin C that is no longer functional in humans.