Yu-Gi-Oh! GX - watch online: streaming, buy or rent
Currently you are able to watch "Yu-Gi-Oh! GX" streaming on Hulu, Crunchyroll, Crunchyroll Amazon Channel, Retrocrush, Midnight Pulp Amazon Channel, Kartoon Channel Amazon Channel, RetroCrush Amazon Channel or for free with ads on The Roku Channel, Pluto TV, Amazon Prime Video Free with Ads, Toon Goggles. It is also possible to buy "Yu-Gi-Oh! GX" as download on Apple TV, Amazon Video.
You can also stream the title for free on Hoopla.