Namco X Capcom was a strategy RPG for the PS2 in Japan. It was a crossover between, would you guess, Namco and Capcom.
This is the opening video from the game, which has a nice little song (Brave New World, which, in the later games they appear in, became the theme song of the original characters Reiji and Xiaomu) and some of the most famous video game characters around (and some obscure ones too; Wonder Momo, Bravoman, and the characters from Forgotten Worlds?).
(uploaded by bass877)
While Namco X Capcom never got localized, it’s sort-of-sequel, Project X Zone for the 3DS, which adds Sega into the mix too, did. It’s pretty good if you like SRPGs and are familiar with a fair number of the characters in it.