Zettai Chikyuu Boueiki Mega Laughter

Gameplay is based on card battles.

Far from the outer reaches of space come the invading aliens called Reticulians. Dr. Tsukitometa claims that the only weakness of these aliens is humor and begins the construction of the giant superrobot Mega Laughter.

Shinichi, our protagonist, who could be called a humour maniac and who sports the worst short-time memory ever seen in a protagonist, is recruited by Muramatsu Pasta (Commander of the EDF) to pilot Megalaughter.
He is assisted by Nanami, who works in the base,
His humourless childhoodfriend Hikari is drawn into the events as well, and soon Liu, one of the elite pilots from the Zeta star system is forced to join them as well after being beaten...

[Translated from Getchu]