Before Obelisk's fists hit, Yami Malik uses Ra's ability to sacrifice the rest of his monsters to increase Ra's attack, and then sacrifices the additional 1000 life points he got from Yami's Soul Taker card. This makes Ra's attack 4899. It seems pointless but...
Obelisk's fists hit Ra, but bounce off and do not destroy Ra or do any damage to Yami Malik, who laughs because he states that Ra cannot be destroyed by the special effect of Obelisk. He prepares to attack Obelisk and wipe out all of Yami's life points...
BUT Yami counters again with his Dimension Magic card. It allows him to sacrifice two monsters to special summon a Spell-caster to the field if another Spellcaster is also on the field. Since Yugi has his Dark Magician Girl on the field, he sacrifices Gazelle and (in a surprising move) Obelisk to bring the Dark Magician onto the field to join his young apprentice. The two Magicians can now automatically destroy one monster on the field. Yami picks Ra and destroys it.
When the cloud settles, everyone sees that the normal Malik is back in his body while Yami Malik is now chained on the field. What happened was that since Yami Malik had been combining his soul with Ra's while performing One Turn Kill, he was weakened. When Ra was destroyed, it severely weakened Yami Malik, allowing the normal Malik to reclaim his own body. However, a sacrifice had to be made, so Yami Malik was put in his place.
Malik realizes now what he needs to do. He forfeits the match, causing Yami Malik to disappear completely.
Yami Yugi is now the official winner of Battle City.