Iron Brigade

Offering my solution to get gold medal for this stage as well as earning the achievement Pylon Pillager.

Mission on Solo (somehow lesser tubes and pylon take more damage.)

Chasis: Karlsson MK II (requires rank 5 and cost $1800)
recommended: Karlsson MK III (requires rank 7 and cost $2400) (armor: 100 pts)

Weapons: S-2 "Ripper" (requires rank 5 and cost $700) in all 6 weapon slots hence will cost $4200)

Legs: Standard Tripod Legs (requires rank 4 and cost $900) (fortify and quickload)

When you get a chance to move (before the next cutscene) quickly move forward and press [A] to station/fortify down your mech. Once the cutscene ends and you get control just unload leads onto the pylon and once it comes out of the shell just target the legs and when they are taken out wait for a few secs and then target the head once the bubble burst. need not bother with the other smaller tubes attacking you as you should have enough armor to withstand the attack especially if you use the Karlsson MK III. May need a few practice to get it right.

The Pylon isn't too difficult to take down. Once it's head has been sheilded, you'll need to take out each of it's legs (four IIRC) to drop the shield before you finish it off.

Sniper cannons are highly reccommended.

Gold Medal time is 40 seconds.