No, he was saying adding Mew in LostGar, NOT Gyara:
"LostGar wins 5th turn
1st: LZ gengar, 1 energy
2nd: Use it's first attck, put in 2 pokemon w/ 2 energy
3rd: First attack, put in 3 w/ 3 energy
4th: First attack, put up to 4 pokemon.
5th: GG."
I assumed that first turn meant he was using Mew to LZ the Gengar.
I'm not sure if any Gyara deck could use Mew Prime as a tech against anything besides LostGar. It just has too little HP to survive against anything that actually does any damage to it.
"LostGar wins 5th turn
1st: LZ gengar, 1 energy
2nd: Use it's first attck, put in 2 pokemon w/ 2 energy
3rd: First attack, put in 3 w/ 3 energy
4th: First attack, put up to 4 pokemon.
5th: GG."
I assumed that first turn meant he was using Mew to LZ the Gengar.
I'm not sure if any Gyara deck could use Mew Prime as a tech against anything besides LostGar. It just has too little HP to survive against anything that actually does any damage to it.