REDU format ruling
Straight Flush

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Activate only when all of your opponent's Spell & Trap Card Zones are occupied. Destroy all cards in your opponent's Spell & Trap Card Zones.
Rulings
- If your opponent controls an Embodiment of Apophis as a Monster Card, it is not counted as a card in the Spell & Trap Card Zone (even though 1 of those Zones cannot be used). So you could not activate Straight Flush.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.