Element Hunters

Both fight with the knowledge of chemistry and elements and use the properties of the elements to fight more effectively. 

Different genres, but both animes are about elements in the Periodic Table. Useful for Chemistry ^_^ 

The OPs are very similar and give similar touchy feeling. Both are about kids on some important mission. Though E.H. has more action, and Blue Drop has more romance and psychology. 

Both Animes feature a group of kids traveling to demensional realms to exsterminate evil monsters,in digimon,7 kids must save the digital world from evil digimon and in element hunters,3 kids travel to a futuristic wasteland planet called Nega earth to esterminate monsters called elements. also,both animes feature kids with high tech devices to fight they're battles 

Element hunters has so many similarities to the digimon series in being able to go to another world to fight monsters.. but savers is the most similar one (excluding the pet partners)