On demonstrablilty, there are the studies of the evolution of fruit flies, but even those studies have only gone on as many generations as perhaps twelve thousand years human scale. There has not been much change in humans in that span of time, one species evolutionary progress does not necessarily equate to another's, and a species adapted to its niche will continue to exist as long as there is no pressure to change. Twelve thousand years is not much time for evolution, measured on scales ten thousand times that.
(The tongue-in-cheek argument is: if the United States evolved from England, why is there still an England?)
Genetics is direct demonstration. Evolutionary theory can be supported today without any fossils at all through the DNA record. Age of fossils can be demonstrated through a number of different dating methods.
On the other hand, we have viruses and bacteria, which can readily be demonstrated to mutate to new environmental loads (think MRSA, extremely resistant TB, &c) as far more generations have passed. Note that every year the seasonal flu mutates to a new virus, flus of one type (bird flu for example) have made the jump to humans, so has Simian Immunodeficiency Virus (now Human Immunodeficiency Virus). There is not ample evidence of evolutionary change, the evidence is overwhelming.
Yet evolution by natural selection could be overturned tomorrow, if new facts came to light that could not be adopted into the theory, or a better theory to explain the evidence came to light. Evolutionary theory is not dogma, as it is falsifiable, as any other proper scientific theory.
Intelligence (as measured by standardised IQ tests) seem to show a slight but upward shift since they were devised. That could be an artifact of testing (the timeframe is very short), or it could be evidence of continuing evolution of the brain; the jury is out.
But, just as I am not a plumber, therefore I consult one when I have a problem with my plumbing rather than say "plumbing has not been proved to work as I have a leak," I am not a scientist either. I have a high school education and edit kinky Romance novels for pocket money. For a proper explanation of evolution you would need to go to a scientist (in short supply in the Nebraska Panhandle).
The argument of "if evolution is true we would expect to see X but don't" doesn't really mean a lot. One cannot argue what you would expect to see, as you cannot know what you would expect to see (although you would not expect to see rabbits in the Precambrian if evolutionary theory as we understand it is true). What is it you are expecting, and why should evolution measure up to what you expect? Scientific enquiry does not advance by finding things you expect, it advances by finding things you don't.
And finding ten transitional forms in species between two and three million years might be harder than you think. The Rocky Mountains are continuing to grow, as are the Himalayas. The Great Plains were created by the Yellowstone Supervolcano's last eruption 640,000 years ago, destroying pretty much all the evidence available around here. The last ice sheets only receded some ten thousand years ago.
Erosion and floods and avalanches and fires and volcanoes and tsunamis and meteor strikes and ice ages and all sorts of other natural disasters occur nearly every day (well, not every day for ice ages, but glaciers are very good at pounding evidence to dust). Spread those out over millions of years and there ain't much evidence left in the geologic record, given the difficulty and particular conditions required to create even one fossil.
There is quite a difference between scepticism and denialism. The sceptic moves off the position of scepticism when there is no serious opposition to a premise. Denialism refuses to accept the given evidence as sufficient, no matter how much evidence is given.
Any serious opposition in the scientific community has been overwhelmed by the huge quantity of evidence, and its dearth for opposing hypotheses. See Evolution at Wikipedia for a better overview than I could ever give, with links to various scientific disciplines that show why it is the best-supported theory in all science.
As I mentioned above, you accept the theory of gravity, or the theory of electromagnetism (your radio works) on far less evidence.
Evolution today has advanced far beyond Darwin (it has evolved).
I don't think I have ever met a fundamentalist but I think they might like interesting stories, like the natural history of birds. A transitional bird fossil was found in slate during the 19th century called Archaeopteryx. It was beakless with the features of a feathered dinosaur and its unevolved wings still had claws so were more like front limbs. In fact, replicas would make interesting coffee tables.
There is an extant bird in South America which still possesses a claw and, as an example for your statement 'everything is a transitional form", a wingless bird in New Zealand and large oversized birds like the Emu. Compared to the long evolutionary route of Penguins, all birds are in transitional form.
An historical view might interest the fundies more than an overly scientific view.
Then there is the issue of the Feathered dinosaur. But those in denial will simply say, as such dinosaurs fit right between dinosaurs and Archaeopteryx, "But what about between dinosaurs and feathered dinosaurs, and between feathered dinosaurs and Archaeopteryx? We need two transitional forms.
What the deniers really want is ten thousand generations of animals who all died on top of each other, and never have the strata be disturbed by floods, subduction of land, plate tectonics, volcanoes, earthquakes, hurricanes, erosion, fire, urbanisation, agriculture, mining, blasting, &c.
Well, you can talk about dogs. You don't even need fossils because the domestication of the wolf and the diversification of dog breeds has all happened in the last 15,000 years.
If that doesn't work you will need to punch the information into them by resorting to physical violence. I know this is the wrong way to educate people but tough nuts require tough measures.