Khan

Why an INT dragon for this? It's annoying, but to be able to use your 129 STR dragons to fight here for a protracted amount of time, they need to be Rallied, and often healed back up. The bosses are very easy once you use Contuse on them, too. Once your INT dragon is level 25, too, its Contuse will do a smidge more damage than your STR dragons' Scratches, so a Contuse + Eliminate will get rid of the Construction Mith, who otherwise will be reduced to 0 HP and not refund your breath!

The very basic of farming this zone with this build is to make your INT dragon the first dragon - ie. putting it in the leftmost slot while forming your team. The INT dragon will eat the first turn bug, and can if necessary cast Rally on either of your other dragons to defeat the 2 Scratch enemies, or it can cast Contuse on the bosses, or use Aid on any dragon that's fairly damaged.

To start out, you'll want to restart until your first turn is all Meditate-users, or only one physical attacker anyway, so you can gather breath without taking too much damage. You'll be able to get 36 breath on both of your STR dragons, and max out your breath on your INT dragon, on the first spawn.

Here's some spawn-by-spawn tips, for ones that require more work than the standard procedure:

Any spawn with ONLY 1 Construction Mith, OR 1 Steelhound, OR 1 Scrapmetal Tracker, OR 1 Sentry Squawker, OR 1 Monkey Wrench:
Have your INT dragon use Contuse on the strong (listed) enemy. Scratch + Eliminate everything else that's a physical attacker, then the Contused enemy, then any Meditate-users.

Any spawn with 2 or more of: Construction Mith, Steelhound, Scrapmetal Tracker, Monkey Wrench, or Sentry Squawker:
Have your INT dragon Rally either of your STR dragons (it does not matter which!). The next dragon will Scratch each listed enemy once, and the third dragon will use Eliminate on them.

Any boss:
Have your INT dragon Contuse the boss, and each STR dragon Rally themselves before attacking. Keep everyone's health up with Aid, and spam Eliminate; you'll be able to get your breath back quickly.