“Ultimate Baseball Kid”’s ATK increase includes FIRE monsters on your opponent’s side of the field.
You can only send FIRE monsters on your side of the field to the Graveyard for “Ultimate Baseball Kid”’s second effect, not monsters in the hand, Deck, Side Deck, Fusion Deck, removed from play, or on your opponent’s side of the field.
You can send monsters to the Graveyard for “Ultimate Baseball Kid”’s second effect that have been changed to FIRE Attribute by “DNA Transplant” or “Scroll of Bewitchment”.
You cannot send a face-down FIRE monster to the Graveyard to activate “Ultimate Baseball Kid’s effect”.
If 2 “Ultimate Baseball Kids” are on the field, and no other FIRE monsters, each of them has an ATK of 1500.