Heliolisk

Heliolisk solves three of the team's major problem matchups simultaneously. Dry Skin makes it immune to water moves and lets it recover HP from rain turns and opposing water attacks, completely walling Basculegion and Rotom-W. Faster than Charizard-Y, it can Volt Switch before Charizard Mega Evolves to bring Pelipper in safely and keep rain up. Thunder hits hard with 100% accuracy under rain and Focus Sash ensures at least one action even if hit. Glare paralyzes fast threats like Eternal Floette, enabling Chimecho to outspeed them. Near-max Speed with Timid nature lets Heliolisk consistently go first against the threats it needs to check.