It would appear as the monsters themselves using the Duel Disk's Solid Vision technology. They would appear lifelike, and would have some weight to them due to being hard light projections unlike the holograms that have been made with the implants. However, they are not real monsters being brought to life here in Synflux, and the projection would burst apart to nothingness if a kaiju either smacked them hard enough, or just outright slapped Manjoume since he's the one operating the Duel Disk.