Before I start talking about the team, I just want to say it's my first time doing this, so sorry if it looks/is a bad team overall.

I really wanted to try mega staraptor, so I put whimsicott for speed control in tailwind and charm to help staraptor, grimmsnarl for barriers and using parting shot in either the opponents or, again, staraptor, then I put mega Charizard Y for eventual denying of opponents's weather and Venusaur to abuse the sun, last but not least I put basculegion for coverage, but couldn't decide if it was better to fully invest in speed with choice scarf or either choice band or mystic water because of tailwind from whimsicott.

I'd really like advice on how to improve the team