Hello, I would like to write "Kata Championship" in kanji. I know the kanji for kata: 形 but I have no idea which kanji would be used for championship? kumite 組手 is for fighting, but I am not sure if it would apply to a kata competition...
形優勝 seems to get some good hits on google, so I'd think that's one way.
形選手権 has its own Japanese Wikipedia page, so that's a good bet.
I would think it has to do largely with what the organizers feel like calling it, much like how you might call something in English a "competition" "championship" "finals" "regional X" etc.
There are a few hits for 形選手 alone [EDIT: Blarg, not looking at what I'm typing]
I think it could have a lot to do with whether you're talking about a match that has been done, or a match that will occur. I think in the case of saying "Kata Championship" like it's something that will be happening, maybe 選手権試合 is a better usage, however, if you're talking about an already won victory, Kouk's answer will suit it better.