Alright so. Mettaton's absolutely going to get in on this to protect Alphys because everything feels like it's going to shit and she doesn't deserve to have anything happen to her.

For his part if any kind of fighting is needed then he is down. THE DOWNEST!!! And since he has some LOVE on him, then he'll likely be happy to use his magic and his sweet robot moves to tear a Null up if it comes at him and protect anyone important to him, or anyone who he's accompanying down hell lane.