Dragon Quest Heroes: Rocket Slime Codes -

The Nemesis Slime tank in Challenge mode:
Press , (x2), , (x2), , (x3), , inside the church.

Knightro Slime tank in Challenge mode
Press , (x2), , (x2), , , , in side the church.

Giggles in Tank Masters mode:
Successfully complete the game. Then, talk to "Meggan", the green Egg Slime in the northwest building of the central part of town.

Gott Schliemen in Tank Masters mode:
Defeat the final Boss and rescue all 100 Slimes. Then, defeat Hooly and the Shogun in the last round of Tank Masters mode.

Schwarzen in Tank Masters mode:
Defeat the final Boss. Then, go to where you defeated Slival on Mt. Krakatroda. Defeat Slival again to unlock the Schwarzen.