Some characters have cosmic which is a game mechanic that was introduced into the VS System TCG with the release of Man of Steel.
Cosmic simply means that the character that has that ability gains a "Cosmic Counter" when it is recruited. So in the case of Blockbuster, he would gain a "Cosmic Counter" when he comes into play and as long as he has that counter on him he gets +3 ATK.
There are exceptions to the Cosmic rule however, for instance, Parasite reads on it that it comes into play without it's cosmic counter and gains a cosmic counter when it stuns a character.
When a character with a cosmic counter is stunned, it loses that cosmic counter. So in Blockbuster's case, he would be a 7/4 3 drop, until he's stunned. After he's stunned he goes back to a 4/4 because the effect behind the cosmic text is no longer in effect due to the counter no longer being on Blockbuster.
I hope that helps.