This forum is closed for good. Expect new things to come.
In the mean time, I recommend you check the following places: VPW2 Freem, AKI Outsiders or MPire Mall Discord servers. If you really don't like Discord, there is the r/N64WrestlingGames subreddit, but there's no active development of mods/hacks there. Sean O'Connor's Youtube Channel is also recommended.
I never saw a Def Jam FFNY or Def Jam Vendetta mod or hack. I would think those games would have more moves than the wwf games since they came after. (sorry btw I'm a noob)
And the PSP had a Def Jam game for it (no idea how good/bad it is , never played it), so i guess someone interested in modding a Def Jam game could start looking into this to see if they can replace texture from the existing characters into actual wrestlers/whatever.