Both strong
Both are powerful (BST ≥ 500)
The Both strong connection is one of the stats & power rules in the daily PokéWired Pokémon puzzle. Two Pokémon are linked by it when this holds: Both are powerful (BST ≥ 500).
It's not directional: it works both ways, so it doesn't matter which Pokémon goes on the left and which on the right. It belongs to the Hard rule set, so you'll only run into it in Hard puzzles.
Stat connections compare raw numbers — Speed, Attack, Defense, HP, base-stat totals and build — so they reward knowing which Pokémon is faster, bulkier or simply stronger.
Examples
Real Pokémon pairs that satisfy the both strong connection:
Venusaur#3Both strong
Charizard#6Both are powerful (525 and 534 BST)
Charizard#6Both strong
Blastoise#9Both are powerful (534 and 530 BST)
Blastoise#9Both strong
Nidoqueen#31Both are powerful (530 and 505 BST)
Nidoqueen#31Both strong
Nidoking#34Both are powerful (505 and 505 BST)