They both have purple hair (only in gen 1 for Agatha's case), their names start with A, and they are both Ghost type Specialist who appear in the game and end up getting in the E4. Sorry about my curiosity, I can be pretty observant at times.
There's no evidence linking these two. While Kanto and Alola are stated to be geographically close, any link is probably unintentional. Purple is commonly associated with Ghost types in the games, explaining their purple hair. There's really no explanation for their names starting with A other than a coincidence or a slight nod of recognition.