Lycanrock and Nidoqueen are your best friends.
Nidoqueen has queenly Majesty which makes it impossible for Magmar and Torcoal to use their priority fire moves.
Lycanrock outspeeds and kills Castform and Sneasel and can't be oneshot by Aerodactyl so it just kills that one too.
Onyx can be dealt with by the grass type of your choice.
Everything else can be sacs for clean switches if you want or even an extra copy of Lycanrock.
(Also the creator made a mistake with the Torcoal and the Torcoal that courtney has is Adamant instead of Modest, so it hits way less hard than it should.)