You could always bring a plushie of said Digimon to help show exactly which one you're doing. Or maybe a small sign?
♪ Cosplays for 2015 ♪
Hange Zoe [Casual] - Attack on Titan
Aiichirou Nitori - Free!
Monomi [Gijinka] - Danganronpa 2
Hiro Hamada - Big Hero 6
Freddy Fazbear [Genderbend Gijinka] - Five Nights at Freddy's