Try investing in training a camerupt that is what did the trick for me keep it away from dragalge, tentacruel and nidoqueen tough those things have nasty atttack that can hurt i badly enough to K.O it
Uh Ace Magnezone is since episode 10 only available (correct me if i am wrong but this is what happens to me) after you beat EL and his Arceusified Ditto.
You have to go to the Area where Saphira walks out of after Noel asks you to look for her and look for the YUREYU key and THEN go back to the good ole Plant