Responses
Lol she's flexing for the sake of it. She's also showing Sabertooth that Fairy Tail isn't someone they want to mess with and showing everyone that Fairy Tail is back. Most importantly, like Natsu said, they're doing it for the guild and all those people who they left behind for seven years.
this is so old but its always bothered me... in the grand magic games, why did erza bother challenging all 100 monsters... like 51 would win her the game... stupid ass honor or whatever left her w a bunch of injuries but all she had to do was secure a victory...