Luis has this recent entry on Mekanda Robot which is actually one anime which I've been pondering on for the past decade (I remember a mecha show wherein three vehicles would attach themselves to the robot's back) but couldn't quite remember the details or the title.
Anyway, as much as super robots are cool, there are those moments where you think either the protagonists or the villains are acting stupid. This isn't an entry about those. My memorable super robot moments are when either the heroes or the villains are acting smart. Let's start with...
5) Go Lion (a.k.a. lion team Voltron): Akira Kogane (Keith) is nearly assassinated by Honerva (Hagar) and is instead saved by Takashi Shirogane (Sven) who dies in the process, leaving no one to pilot the blue lion unit. No blue lion = no giant robot.
4) Getta Robo G (a.k.a. Starvengers): The enemy sends several robots that combine to form one menacing beast. Combined, they attack Getta Robo G. After a heated battle near the ocean, Getta Robo G finally uses his finishing move (Getta Beam!) hoping to destroy the monster. The monster disassembles just before it gets hit and flees into the ocean, making it appear as if the monster was destroyed.
3) Voltron movie: The Japanese studio made a Voltron movie for the US market featuring both team-1 and team-3 Voltron (i.e. space team and lion team). Near the end of the movie, the two super robots face off against their enemy: four robeasts who surround and nearly defeat both robots. It is only spoiled by the fact that a few minutes later, Lotor in his own robeast appears and combines with the four other robeasts to form one huge robot which easily gets dispatched (never trade your numerical superiority!).
2) Mazinkaiser OAV: Mazinger Z eventually gets overwhelmed by wave after wave of robots. One of them aims for the spaceship atop Mazinger Z's head, where the cockpit lies and breaks through the glass and nearly harms the pilot. Now that's what every villainous robot should do!
1) Shin Getta Robo OAV: Shin Getta Robo is comprised of three vehicles that combine in various permutations to form a specialized super robot. It faces off against its villainous doppelganger which also has the same capability. The fight goes on, with one robot getting the upper hand until the other robot changes forms to gain the advantage. After several minutes of this hi-tech rock-paper-scissors game, the good guys finally smarten up and just before the enemy finishes combining to form a new robot, they get in between two of the vehicles to prevent them from combining into a new form.
Honorable Mention: Although not strictly a super robot, in the live-action show Justirisers, the alien invaders send in a necromancer kaiju (giant monster) to face off against our heroes. He is accompanied by two previously-defeated kaiju so it is a three-on-one fight. Despite the numerical disadvantage, the Justirisers manage to defeat two of the kaiju, only to be shocked when they get revived. Perhaps the only more adrenaline-pumping moment is near the last episode where the alien invaders act like actual alien invaders and send in wave after wave of paratrooping giant robots against Earth.