Pokémon UNITE Charizard has a few options with his build you can consider. Typically, you will see Charizard taken in the bottom lane, but can work in the central lane or even the jungle.
Pokémon UNITE Charizard Build
No matter where you decide to take Charizard, the plan is relatively the same: play defensive and farm wild Pokémon when you are Charmander and Chameleon. Charizard's biggest downside is he takes a little bit to get online, seeing as his basic evolutions are a lot weaker than his final one.
Similarly, Charizard's game plan once you reach the final evolution remains much the same no matter the role: auto-attack enemy Pokémon to death and set up for your team with your UNITE move.
Fire Spin will be your first move to pickup, allowing Charmander and Chameleon to farm well and reach the late-game faster. The other moves you want to slot in for Charizard are Fire Punch, Flare Blitz and Seismic Slam for your UNITE move.
Muscle Band, Attack Weight, and Energy Amplifier seem to be three very strong held items for Charizard, really trying to push the auto-attack focused nature of this build.
You can also consider swapping out Energy Amplifier for Float Stone, but the out of combat movement speed from Float Stone is not as strong as the temporary boosted power after using your UNITE move from Energy Amplifier. Charizard's key move that can outplay opponents is his UNITE move Seismic Slam, so Energy Amplifier will likely come out on top over Float Stone most of the time.
This build provides Charizard with a lot of bonus attack damage against tanks, squishies, and provides a nice boost in power after using Seismic Slam.