Okay so I really fucking suck at team building, and I'm fucking sick of losing all the time.

Help me build a team of six, and tell me what combinations work when I have to choose three for ranked matches.

Bonus points if you explain why the choices are made so I can understand and make these choices on my own without asking in the future.

>Chansey
>Mawile (Mega)
>Reuniclus
>Slowbro
>Raichu
>Goodra
>Gengar (Possible Mega)
>Vileplume
>Greninja (Protean)