Rokumon Tengai Mon Colle Knights

In both series: - a boy and a girl need to catch/save monsters (in Flint the time detective, Flint will help the main boy and girl character) - need to travel to a different world to do so - get help from a weirdo, but funny professor - the bad guys exist out of a bossy leader who can be angry quickly and two helpers.  

They both have this strange kind of humor, but in Disgaea it's a bit darker, because it takes place in the Netherworld. Both animes have this 'love' issue, in Mon colle Knights it's jealousy, in Disgaea they don't seem to understand it. If you plan on watching Makai Senki Disgaea, know that the episodes are much easier to find then with Rokumon Tengai Mon Colle Knights.