Sonic Adventure 2 objects
From Sonic Retro
Omochao will act as a guide throughout the game and can be found at various locations inside each stage. Touching it will make them follow the character around, giving an advice of some sort. As a character fails a boss fight, one will usually appear with some advice as well. Any speed or hunting type characters can hold them, but Omochaos don't like it and will whine about it immediately. A character can throw Omochaos at enemies to destroy them, just like any item. The Omochao will whine about it but it will not be destroyed (though it can be out of it for a couple of seconds).
Big the Cat
Big the Cat has cameos in every single level on the Dreamcast version, doing an activity of some sort (fishing and jumping are the most common). He appears once per level (except White Jungle where he appears twice; Weapons Bed in Hard Mode where he has a second appearance; Route 101, Route 280, and Green Hill, with no appearances; and Cannon's Core, appearing once for every character). He's usually at an unreachable place, but there are some who can be reachable. Sometimes, he switches positions slightly or changes locations completely in Hard Mode.
Big also appears in one boss, the first one against Shadow. He's down below in a cage part of the ground.
These cameos were removed from the Gamecube version and sometimes, a ring will be in his place instead, which might be obtainable or not. Even so, Big can be seen in some cutscenes by pressing endlessly.
The third mission for every level is to find a Chao hiding somewhere on the level. Most of the time, the Mystic Melody upgrade is needed. The Chao wil either be confused and crying while not found (as in, the character not touching it), or jump in happiness with a heart on top of it's head when found.
There's a total of 21 types of small animals that can be found inside Badniks, inside the second and third Chao containers, and in several locations in each stage. Their function is for Chao raising, just like in Sonic Adventure. There are five different types in each stage, with four being common animals and the fifth being a rare or special animal, found in hidden or difficult to reach locations and in the third Chao container.
Collecting small animals awards no points, but collecting any small animal other than one released from a Badnik or Chao container will add to a running tally for the stage, and if this puts the stage's tally up to a designated maximum value (20 when playing as Sonic or Shadow, 15 as Tails or Eggman, and 10 as Knuckles or Rouge), it's awarded an extra life.
Like in the majority of Sonic games, rings appear scattered across every level and boss arenas, with the exact same survival function as previous titles. In contrast to previous games, there's no score tally at the end of the level for Ring Bonus; rather, each ring collected scores 10 points immediately (with the exception of rings recovered after a hit and rings rug up from the ground, which award no points). They appear clumped together inside item boxes and collecting sets of hundreds will award an extra life, as usual. For shooting levels (Tails and Eggman), survival is a consequence of a health bar, and each ring collected will recover some lost health. One ring recovers 1/70 the span of the health bar, or 1/80 for Eggman after collecting the Protection Armor.
Every level has a prespecified ring total for missions 1 and 4, and another for mission 5 (the total is meant to correspond to the number of rings in the level, and usually does, but can be off in either direction in some levels). Collecting enough rings in the level to match or exceed this total will award an A-Rank to that mission, regardless of the score. When rings are awarded at checkpoints, dug up from the ground, or thrown by enemies who would otherwise throw bombs, the required total goes up by the same amount, in order to prevent scalping several hundred rings from the ground in a hunting stage for an easy A.
Since Big the Cat is not present in levels in the Gamecube version, sometimes a ring will be in its corresponding place. Even though it’s not obtainable in some cases, the ring is factored into the required A-rank total in every case where it appears.
Like in the majority of Sonic games, item boxes appear scattered across every level and boss arenas, for holding items. The same spherical and transparent containers from Sonic Adventure are used, albeit they’re slightly redesigned. The number of items and their bonus is the same, though there’s no random ring box and there’s a new first-aid kit one. Dying will respawn every item, except the extra-life, which will appear as a blank container. By contrast, restarting from the pause menu will respawn everything including extra lives. Note that the point values aren't awarded for items dug up from the ground. It should be noted that there are item boxes that are hidden from normal view, for Knuckles and Rouge, and only accessible by using the Sunglasses or Treasure Scope respectively.
Giant red balloons also work as item boxes, though the prize is not visible. Knuckles and Rouge can also dig into the ground and occasionally pull out any item box rewards, except Invincibility and Health. (Additionally, ring boxes cannot be dug up during Mission 2,)
Hunting Stage objects
These are always a set of three objects that either Knuckles or Rouge need to find to complete their levels. Collecting any of these objects awards 500 points, and possibly bonus points on top of that depending on how quickly it was collected after the previous item, and how many hint monitors were used.
There're also radar monitors, which are television-like objects that will give hints as to where the hunting objects are (only three per location). In Mad Space, the hints are reversed (either by reversing the order of letters or reversing the meaning). There are monitors that are hidden from normal view, for Knuckles and Rouge, and only accessible by using the Sunglasses or Treasure Scope respectively.
GUN robots will drop one when destroyed. Their function is for Chao raising. Additionally, collecting a Chaos drive awards 10 points, and in the case of Tails and Eggman, recovers the same amount of health as a ring does.
These are cubic boxes, of various materials and functions, that appear scattered across every level and some boss arenas. Some might be in blocking paths, others hiding item boxes or animals. Destroying any container awards 20 points, except in Crazy Gadget where they score nothing because the containers in that level are an entirely different object (because of their reaction to gravity switches) and they were never given a point value as such.
These containers are of a light blue colour and there are always three of these containers per stage, except Green Hill which only has one. Destroying one awards 20 points, even in Crazy Gadget, and either contains a Chao Key or animals.
Level status items