Charizard @ Charizardite X
Ability: Tough Claws
EVs: 248 HP / 100 SpD / 160 Spe
Careful Nature
- Will-O-Wisp
- Flare Blitz
- Roost
- Dragon Claw / Earthquake
Mega Latias is probably the ideal final member, but here's something anyway! Zard-X provides a few interesting things. For starters, despite running a more defensively oriented set, Zard-X still sports a good deal of the offensive presence this team would appreciate. Furthermore, it's able to help with troublesome threats like Zard-Y, who messes with your sand and looks very threatening overall. To add, Zard-X pressures a few annoying grasses for this team, such as Mega Venu, Loom, and Serp lacking Dragon Pulse. Zard-X also provides a tool versus defensive Pokemon like Skarm and Mew. Currently, Skarm can Spike pretty freely on every member bar Jelli, while Mew can essentially lead turn 1 and give this team a headache from the get-go. With Zard-X on the team, this all becomes less of an issue.
This all aside, Zard-X does a nice job spreading burns, which is nice with residual damage like sand and hazards on your side. This is also useful to cripple grounds like Lando-T, something Exca will love. Having Pokemon like Lando-T burned makes life easier with wearing down the opposing team's SR setter, helping with the hazard removal game in the long run. Zard-X's ability to burn defensive waters like Slowbro is another way Exca benefits. If running EQ, Zard-X can also potentially lure and eliminate Tran for members like Clef. This is helpful because although the team has a few ways to threaten Tran, nothing really likes switching in between the threat of Toxic, Lava Plume burns, and Taunt. Dragon Claw is the main choice to reliably damage Zard-Y, and to give hazard removers like Latios fewer chances to freely Defog your Spikes. It's also useful to threaten Rotom-W better, which is helpful because this Pokemon is pesky for every member bar Clefable.
To round things off, Zard-X gives this team some additional ways to check Pokemon like Bisharp, Mega Scizor, and Thund-I. The checks on a team like this have a tendency to get overwhelmed in practice, so having some backup measures can definitely be useful. Downsides to Zard-X include having its success hinging on how well SR can be prevented, and being unable to provide an additional check to offensive waters Keldeo and Manaphy unlike Mega Latias.