Warning, unsurmountable amounts of autism in the following reply.
>>28027722I guess you're right in that sense, while the Snowbelle arc the focus was on Ash and Greninja(to a lesser) extent it's interesting what they did with Serena, because in a way it too might've been a test for her feelings towards Ash, for one even though Ash shut himself of getting any aid from her(or anybody for that matter but she's the one that tried) she got mad at him and reacted somewhat violently, but the reality is she couldn't stay mad at him for too long, that's because she's unconditional to him and feels the same for him regardless of what happens, also I guess it's more that she was frustrated because she wanted to help regardless but it didn't seem she was being any help at all(even though it turned out she did help) and so she felt bad because she thought she outright might've made things worse. Then later on until Ash thanked her for the "help" she still felt sorry for what she did, and in the beginning of XY&Z29 was still worried for him, but throught the episode she was relived to see that Ash wasn't bullshitting her but it was true, she managed to help and as by her own words in later episodes Ash not only returned to his hold self but was in fact better than before.