Which kinds? There's like 50 types of Maser Tanks! If you mean the Showa ones, Gaira destroyed one type. Some more drove off Anguirus, but I'm pretty sure Gigan, Megalon, and ShowaGhido weren't very affected by them. If you mean the Millennium ones, Godzilla destroyed those pretty easily. The Heisei ones weren't very good against Godzilla either. The only monster they killed was Destoroyah, but IIRC, that was because they made it a freeze cannon instead.