Since Oversoul is mostly used in a Elemental HERO only deck, one of the better ways to send a normal Elemental HERO is through Blazeman's effect. Use Blazeman to send Elemental HERO Neos from your deck to the grave. This will make Blazeman's attack and defense the same as Neos. You can then use Oversoul to special summon from your graveyard. Alternatively, you can use Blazeman's effect to send Elemental HERO Necroshade from your deck to the grave, so that you can normal summon a Neos later if you get him to your hand.
Special summoning them is useful to fusion summon another monster. If you already have the other monster material on the field, or by using fusion substitute like King of the Swamp, you can attack up to 3 times.
If you use blazeman to send neos to the graveyard, it wont let you activate this card from your hand in the same turn. Tried it twice on back to back duels. didnt work. It might work it its set before using blazeman. Will try that.
In a Duel I cant use it eventhough i had 3 normal elemental hero monsters en my graveyard (Neo, burnitrix and Sparkman, the actions before were: I normal summon a monster, they chain champions vigilance, my monster were destroyed, My oponent only had in the field blue eyes and blu dragon summoner. I was supposed to be able to use o oversoul.
It wasnt. I summon blazeman the turn before, then send neos to graveyard with the effect, my opponents turn summon blue dragon, he attacked me with blue eyes and blue dragon and destroyed blazeman, he set champions vigilance and ends his turn. My turn i draw ellemental hero heat, use jaden skill to use the field that makes my elemental gain 1000 attack poin and then happend what i explained before