Yes, you can replace any or all flaked barley with pearled barley, 1 to 1.
Flaked barley still has some bran and pieces of husk in it (the small brown patches), pearled doesn't. When used in the mash, I would not expect much or any perceptible difference between either, or in the resulting beer.*
So use what's easier available or lighter on your wallet.
* Just a thought, no research or evidence. Pearled barley may be fresher tasting, due to being less processed and oxidized, being small, hard kernels with far less surface area than flaked barley. Something that may also appeal to LoDO brewers.