*WARNING* Keep Element on meks at all times! As long as your mek is out you must have element on it otherwise it will despawn/die. 1 Element per day it is out seems to be enough. I've lost 2 meks with no trace even in tribe log because of this.
2 things: 1. Base level Mek are 51, unlocked at level 91, with blueprints for higher levels obtained through the normal way (titans or OSDs). 2. They starve without fuel, and need element to sustain themselves.
When creating the Mega Mel for Alpha King Titan you must defeat Beta King Titan First to get the attachment to make a mega mek. A mega mek requires 4 meks to combine as one. You can use the base level 51 meks to create the Mega Mek. Once the fight is over you lose all 4 meks that you have used. So advised to use 4 level 51s as stated.