Winning a whole Tournament with Goomy will not make Ash look like a Opt if he uses proper tactic .
You're talking as if its absolutely impossible for Goomy to win a whole Tournament unless its evolve.
However , If Goomy win the whole Tournament using only one move without getting a single scratch Then it will Haxing. (Almost like Trip's Serperior)
Goomy can be strong if it learn good move and if Ash use tactic like Teaching Goomy ''Sludge Wave'' and using it at the right moment in order to beat Gardevoir.
Or using ''Muddy Water'' as Barrier , Bringing back ''Counter shield'' and use ''Frail'' as trump-card to win the final round .
You do know that Frail power can reach 200 if the user is seriously injured .
Plus , if Clemont's Bunnelby almost dominate Pikachu despite it being his first battle then why Can't Ash's experience play any role in Goomy's power.
Plus , Goomy need to reach level 40 to evolve so if Ash's Goomy evolve with only 3 days training then it also would be haxing .
I think That abusive trainer should also point this out that Goomy takes too much training and too much time to evolve so it much better to find and catch a wild Goodra instate of raising a Goomy.