If you’ve got a bag full of Potions and Revives then you should never find yourself in a situation of one Pokémon between you and failure. It’s all about being prepared.
Whilst HM’s aren’t needed for the main story, if you’re going exploring the vast wilderness of Unova it’s essential to take a flashing, cutting, surfing boulder pusher with you as it will ensure you’re always able to make progress.
If you make sure you have lots of items such as Repels and Escape Ropes on you at all times then it can guarantee a swift escape in the worst of situations.
Pokémon Gold & Silver added a day and night cycle alongside a real time ‘week’ with unique events that would only occur at specific times.
Black & White retain these two ideas but add seasons, spring, summer, autumn, and winter, which change every real month and bring with them a host of cosmetic and gameplay effects.
You can only access certain areas by climbing snowdrifts, for instance, while Deerling and Sawsbuck have a different appearance depending on the time of year.