Green is aiming to remove the occupants of Heroes Loft and its workers. Before he can begin dispatching the carpenters, he aims for the main defense and either destroys or disables it so that they will not act as an interference.
As far as why he is doing it, When the officers arrive to take him away, he'll start spouting gibberish that will weave together later.
Green uses a mix of Dark and Grass type pokemon. He is a Ruin Battle type, so basic opposing elements on his pokemon won't work, your still able to exploit the other weak ends however, check the pokedex or bulbapedia. I'll tell you 2 other pokemon on him, I prefer to save the other 3 on his belt for later in this plot.
This will not be a simple battle. As I said, the exiles are retired E&S elites. They aren't push overs and neither will be this fight.
Mightyena
Immunities:
Fight-Type moves
Moveset:
Roar
Hyper Beam
Fire Fang
Ice Fang
Cacturne
Immunites:
Bug
Fire
Moveset:
Seed bomb
Energy Ball
Solar Beam
Fling