Their ability to be Normal Summoned can be exploited with "Skill Drain", which negates their self-destructing effect. They work well with "Begone, Knave!", which returns them to the hand instead of sending them to the Graveyard. You can also use "Altar for Tribute" to gain large amounts of Life Points.
There is also one Zombie counterpart and a Pyro counterpart of the "Majestic Mechs": "Malevolent Mech - Goku En" and "Pyrotech Mech - Shiryu". There are no other "Malevolent"/"Pyrotech Mechs", but their effects allows them to be Summoned with less Tributes. Nevertheless, Summoning them this way has some drawback related to their Types: "Goku En" is destroyed and sent to the Graveyard at the end of the turn and deals damage to your Life Points, unless there is at least one other Zombie-Type monster on the field, while "Shiryu" burns 1000 of your Life Points each turn.