Both mono
Both are single-type
The Both mono connection is one of the types & combat rules in the daily PokéWired Pokémon puzzle. Two Pokémon are linked by it when this holds: Both are single-type.
It's not directional: it works both ways, so it doesn't matter which Pokémon goes on the left and which on the right. You'll meet it in Normal puzzles, and it can also show up in the Unlimited and Chain modes.
Type connections are the backbone of most chains — they ask about a Pokémon's typing, its weaknesses and resistances, and how one type fares against another in battle.
Examples
Real Pokémon pairs that satisfy the both mono connection:
Blastoise#9Both mono
Raticate#20Both are single-type
Raticate#20Both mono
Arbok#24Both are single-type
Arbok#24Both mono
Raichu#26Both are single-type
Raichu#26Both mono
Sandslash#28Both are single-type