Tengu format ruling
Elemental HERO Bubbleman

Card effect (current official text)If this is the only card in your hand, you can Special Summon it (from your hand). When this card is Summoned: You can draw 2 cards. You must control no other cards and have no cards in your hand to activate and to resolve this effect.
Rulings
- Missing the Timing: If "Elemental Hero Bubbleman" is Summoned by an effect in the middle of a chain, you will miss the timing and cannot draw the 2 cards.
- You can only use the effect of "Elemental Hero Bubbleman" to Special Summon itself during your Main Phase.
- If you choose not to draw 2 cards for "Elemental Hero Bubbleman’s" effect, it does not start a chain.
- If "Elemental Hero Bubbleman" is destroyed and then Special Summoned by "Rope of Life" in the Damage Step, if there are no other cards on your side of the field, you can draw 2 cards for the effect of "Elemental Hero Bubbleman".
- If you Special Summon "Elemental Hero Bubbleman" by the effect of your opponent’s "Last Turn", you can draw the 2 cards.
- If your opponent chains to the effect of "Elemental Hero Bubbleman" with an effect that causes you to have cards in your hand (such as "Conscription"), then the effect of "Elemental Hero Bubbleman" disappears because you must still have no cards when resolving the effect.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.