TR-32 Variable

Switching to Fighter form will cause any abilities and spells already on the stack targeting TR-32 Variable to fail.
When switching between forms, mods and lifepoints are carried over. Thus, if you use NM-85 Nanomachine while in Mecha form, you can increase the lifepoints for the both forms. Conversely, this means that any damage in one form will transfer to the other form.
When switching forms, the attack is either multiplied by 3 or divided by 3. Thus, any increases to Mecha form will have a much smaller impact on Fighter form, and any to Fighter form will have a huge impact on Mecha form.
Increasing Fighter form's base attack is difficult due to the Ability and Spell Shield. modifiers, Morale and Open Heart are just a few ways to accomplish this, however.
Fighter form's Quick Hit make it useful for finishing off weaker monsters, while the Mecha form makes it easy to weaken them in the first place.
After switching back to Mecha form, TR-32 Variable will still be undizzy, despite Mecha form lacking Speed Summon. This is the case even if the likes of Active Time are in play.

Card History

Oct 20th, 2006: Card released in Mechanical Chaos.
Feb 13th, 2007: Fighter form changed to ignore the "cannot be undizzied" ability of Active Time when undizzying itself as it reverts to Mecha form, instead of failing to revert.
Aug 13th, 2007: Details in forum post
Aug 18th, 2007: Fighter form fixed to have Quick Hit not trigger when zero damage is dealt due to Protect and "takes no damage until end of turn" abilities.
Dec 17th, 2008: Details in forum post
Dec 20th, 2008: Fighter form's stats changed to 20/35 from 12/35.
Jun 10th, 2011: Mecha form's monster type changed to mecha from robot.
Apr 17th, 2012: Monster type changed to robot from mecha.