Adventures Red is skilled enough to equally matchup to Ash, and has experience comparable to Leon and Cynthia, but Ash is simply far more powerful and has enough to skills to battle him equally, so it could go either way.
Adventures Red is more than used at fighting in circumstances that Ash isn't, like fighting against trainers trying to literally kill him and his Pokemon, so he will have a type of experience that Ash and the others simply don't, as he's also acquainted to fighting things a billion times stronger than him like Mewtwo and Deoxys and outwitting them.
He's the strongest, best written, and most skilled incarnation of Red to date, but even then I feel like the battle could go either way with 1 gimmick for each, and on Ash's favor if he can go all-out.