“Bubble Shuffle” is an effect that targets 2 monsters.
If either target of “Bubble Shuffle” is changed to Defense Position or removed from the field before “Bubble Shuffle” resolves, the entire effect of “Bubble Shuffle” disappears.
You can target the opponent’s “Elemental Hero Bubbleman” with “Soul Exchange” and Tribute it for “Bubble Shuffle”.
If there is no monster in your hand with “Elemental Hero” in the card name, you cannot activate “Bubble Shuffle”.
You need a face-up Attack Position “Elemental Hero Bubbleman” on the field to activate “Bubble Shuffle”. If he’s in Defense Position you cannot activate it.