If you control more than one face up "Dupe Frog", your opponent will not be able to declare an attack, creating a lock-down on attacks. If you have one "Dupe Frog" on the field, use "Slip Summon" to get another during your opponent's turn, stopping attacks for that turn.
If you equip "Mist Body" to "Dupe Frog" you can create a good defense, since "Dupe Frog" can be placed in Defense Position and draw all attacks to it.
If this card's effect is negated while it is on the Field, it will still activate when sent to the Graveyard.
However "Dupe Frog" will miss the timing if used as a cost, such as being used as a Synchro Material Monster or if it is tributed.
If you have another monster on the field, equip it with "Raregold Armor" to stop all opponent's attacks.
Normal Summon "Junk Synchron" to Special Summon "Dupe Frog" from your graveyard. Then use "Inferno Reckless Summon" to Special Summon 2 more copies of "Dupe Frogs" to your field (since the effect of "Dupe Frog" that treats him as a "Des Frog" is negated).
You can then Synchro Summon using "Junk Synchron" and "Dupe Frog" (who lost its effect) for a 2500 ATK "Junk Warrior" (or 4900 ATK with "Wetlands" on the field) and your opponent cannot attack you because you have 2 copies of "Dupe Frogs".
You can set "Dupe Frog" and "Broken Blocker", then after your opponent eventually destroys it by battle, you can activate broken blocker to summon two "Dupe frogs" from your deck (since it's name is dupe frog again). You can then add a Frog monster from your deck to your hand, and your opponent cannot attack.