A commonality throughout, is that all games begin with floor-based simplistic enemies.
The 2D games have a range of sentry, airborne, high-mounted, projectile-based, projectile throwing and vertically travelling enemies in the very first levels, and evolve and add to this throughout the game.
Crash, Mario Sunshine, Jak and Daxter and Sonic Adventure, tend to keep things *much* safer to begin with, restricting enemy types to those who are floor based with only Sonic Adventure going so far as to add a projectile throwing enemy and a few aggressive attackers in its first few minutes of gameplay.
All games also have static environmental hazards – spikes, blades, etc… - and bottomless pit Kill-zones as standard, with the occasional game having a hazard that ‘contains’ and surrounds the gameplay area – like a bottomless pit or an ocean you can drown in or get eaten in.
Sonic is unique in that it contains hazards related to the way the character interacts with the environment’s shape. For instance, jumping on a sloped area – when in the confines of inertia/momentum - could send you flying into a nearby hazard - being as the angle of the slope relative to your speed alters your trajectory and jump range significantly.
Mario Sunshine and Jak and Daxter’s kill-zones don’t come in till later in the game and it’s fair to say the majority of hazards in both titles – at least within the first parts of the game - are enemy based, as opposed to environmental and very minor in threat.
2006 Addition: NSMB sticks to the simple enemy formula, even so far as simplifying it slightly to have only shelled, bouncing and horizontally walking enemies – no spiked ones. It now uses platforms as hazards too, with some see-saw platforms causing you to fall to your death if stood on for too long.
Score bonuses also seem to have declined in popularity over time with Mario Sunshine, Crash and Jak and Daxter replacing score with finance and Quota Token count.
Sonic Adventure however, has decided to keep a score feature, using it as a way to grade a player’s game-play performances.
Games which don’t use a score system for unlocking areas or granting bonus Quota tokens, tend to hide Quota tokens in HTR areas, or simply place a sub-series of Quota tokens within a combination of standard, hidden and HTR areas for the player to collect.
In simpler terms:
Mario Sunshine used the new system in an arguably crude fashion, using three different types of finance - merely different in colour, Quota amount and in ease of discovery – as ways of unlocking further Unlock/Quota tokens, which would then grant you access to later levels and game events.