Wattcannon is old card, but there are two reasons why it won't work. Of course, because it checks type. Also in its current text, because it says "to the field", it would do nothing. Even if DNA Surgery was being applied with the correct type, Wattcannon must still check the card type, and is still illegal activation.
BTH is tough. But simply put, it wont work, and again, 2 reasons, because of the ATK check, and for a 2nd reason you probably didnt think of. Just because the monster isn't on the field when they're summoned doesn't mean they haven't been summoned, so the activation is correct if you ignored the ATK issue, however, I'm looking at Iron Wall VS BTH. BTH would banish a card on the field, and since you can't activate a card that would do something that would be illegal activation, in which case, sending a card from the field elsewhere when there are no cards on the field, BTH can't be activated.
Floodgate Trap Hole can be activated and will resolve normally, because it doesnt target, doesnt send a card on the field anywhere, doesnt check anything from the monster to activate, and the field spell doesn't activate, so it doesn't miss timing.
Say your opponent had Yami on the field, and you had the new field spell. Their monsters wouldn't gain the ATK boost, because the opponent's Yami can't check the type, level/rank/link number, link markers, card type, or stats.
Also. Because they aren't considered on the field, this means multiple monsters can effectively occupy the same monster zone. However, cards that check monster zones or use them, like Senet Switch, Blasting Fuse, cant be activated. But, Link monsters can still be used. Despite this, you can still Summon multiple Synchro/Xyz/Fusion/Link monsters into your single EMZ, instead of the Linked Zones. If Yami Okoku, the new field spell, leaves the field, the player would select one of these monsters to keep, and send all others to the Graveyard, as per game mechanics.
Edited by frenzyhero, Yesterday, 02:09 AM.