It doesn't really look like trade show pamphlets that I remember from the era (minus the times some companies would print up extras and give them out as swag at trade shows, especially if they had posters on the other side.)
It looks like an old mini catalog that would come with a toy, showing what else you could get.
The mini figures that are shown in the first image are one of the sets shown in the catalog in fact (minus the gold chase/bonus figure of MetalKabuterimon, which based on info was from a slightly later set. Either it got put in the wrong set by an owner at some point, or at some point the figure distribution was mixed up during a reprinting, potentially to just only have one set of chase figures being made at any given time.)
The fold out catalog (and the card as a bonus) were likely in the packaging with the figures in their original release.