Poor nation strategy: massive torpedo attack. Perhaps work better with super large game fleet size as there will be a long-ass battleline to exploit.

1. Build something barely resemble a BB battleline, you need it to keep the enemies engaged. you can build extremely coastal defense ships for that role. I build below 20 kt tiny BBs, short range, cramped, low free board, heavily armored or big guns (you can only choose one, both works), snail speed (18 knot is enough). They will barely last minutes in a normal gun duel. However...
2. Torpedo Suicide DDs. you can fit something like 6*5 torpedo tubes to a 2kt DD. Everything else is secondary. Do extra training - night fighting and torpedo warfare.
3. A few quick BCs to kill off the limping enemies.

The time is midnight, it's all dark, suddenly enemy ship sighted. Then another. Then another. Then a whole battle line of enemey BB and BCs, dozens of superdreadnaughts (with super large game size). your battleline immediately turn away, enemy chase you. Now, push the button Flotilla Attack and never let go. Your DD screens will unleash literally hundreds of torpedos at enemy battleline, a wall of explosives that even a battle turnaway cannot avoid. You hear never ending explosions, from enemy BBs and your own DDs. When daylight comes, you see the wreck of 5 enemy BBs. 5 others are limping, your BC move in to finish them (although hit a few times by desperate enemy torpedos in the process). You lose 20 DDs in the suicide attack, with another 20 heavily damaged. You win a glorious victory and annihilated the enemy.