Hello,
Out of my current pack of dogs, one has to use a slow feeder. I use the plastic one. I only use metal for all of the other dog bowls (easier to clean), but for the slow feeder, the plastic is cheaper and I like the design. A normal time is 30 seconds for a one cup kibble. Using the slow feeder changes to 90 seconds. Just slow enough to prevent bloat from super inhaling food.
Bulldogs don't chew food like other dogs.
Regarding training and feeding, I don't see how that changes the eating habit. It only delays for a few seconds. They will still eat just as fast.
Behavioral modification is suggested.
Not making a big deal about feeding, no noises, high voices, shaking the bowl, etc.
Changing how they are fed. Pouring food, but them waiting. Leave the bowl on the counter and go about other activities. Minimize the excitement of eating.
Others might have suggestions.