Sure. Although you don't _have_ to use canon Knights, or even canon Digimon, (fanmades/recolors/variants are cool with me.) but if you want, you can.
I'd like to see your CS/know how you'd play Jesumon before you use it though. Mainly because Bandai itself wrote it/him sorta like a Mary-Sue with not-the-best lore connections, in my opinion.

Also, there's a lot of dragons already, so anyone who wants a beast/bird/plant/machine as a Knight is welcome. I might make sure there's an Ice/Beast Knight myself. Well, Sleipmon is an Ice Beast, but well, lupine I guess.