The challenge for EV, despite any difficulties, includes the challenge of transitional species. The whole idea is that a particular transitional was a successful adaptation that lived, breathed, roamed the earth for ages. Evidence against is an issue that simply needs to be accepted as detrimental to the EV case.
Remember that in determining the likelihood of a non-repeatable event we can only collect evidence. The evidence can include that which supports and that which counters.
Evidence For + Evidence Against = Level of Confidence
In terms of evidence that demonstrates that a particular item has been designed rather than randomly, naturalistically assembled, we can look at items which we know to have been designed and assembled and see what characteristics these designed items share.
Designed items have variously form, function, inter-relating parts, systems, inter-relating systems, non-random ordering of components, etc. A car, for example, has a form, a function, all the above... If the world were destroyed except for a car kept in a time capsule, a visiting intelligent life form could eventually determine that it was a product of intelligent design, no matter how primitive.
Life as we know it on earth shares these characteristics of other items we know to have been designed.
As Alamo-girl has carefully explained, the information systems within living organisms are so complex that they entirely defy randomness.
Personally I do not have a problem with accepting quantizations of a continuum, but one of the most credentialed mathematicians here on the forum has assured us time and again that it is a fallacy to quantize a continuum. As an example he asserts that some are considered rich if they make $100,000/year - which means a guy who makes $99,999/year is not rich.
The fallacy was asserted to derail an investigation into abiogenesis - the theory of life from non-life. The assertion was that it is a fallacy to quantize (define) either life or non-life/death. Our response was that if you don't have a definition for either end for the theory, there can never be a theory of abiogenesis anyone could take seriously. Thus the investigation died.
But if the fallacy applies to abiogenesis then it also must apply to evolution theory. And here it is more troubling because the theory itself is a continuum based on the quantization of another continuum. If one accepts that quantizations of continuums are fallacies per se - how can anyone take evolution seriously? After all the theory of a continuum of life is based on the quantizations (fossils) of a continuum (geologic record).
Personally, I'd like for everyone to ditch the fallacy of quantizing a continuum as cause to dismiss evidence (e.g. fossil evidence, life v non-life/death) and rather consider the quantization a fallacy only when it is used improperly in the analysis.
In the case of fossil evidence, which are quantized from the continuum, I would rather they be matched against a feasible model for the rise of autonomy, semiosis and complexity. If they don't fit the model - then either the model is bad or the evidence is bad and one should try again. If no model fits, then Occam's Razor indicates intelligent design.
Archeology, anthropology and Egypology (along with other historical sciences) face the same quantized evidence problem but do not have a comparable capability to test theory in mathematics and physics.
Well said, xzins!