Sonic Vs Shadow (2P)
From Sonic Retro
The 2P Action in Sonic Adventure 2 for Sonic and Shadow is essentially the same as going through a level in 1P mode, without the Bounce Bracelet and Magic Gloves, rendering both characters the same abilities and also removes the Flame Ring and Mystic Melody. Level objects such as animals, pipes, Mystic Melodies and Chao Containers are removed as well. Each defeat counts as one round and the way to win the battle is by the best of two rounds in Racing mode or just one in Stage Select mode by reaching the goal first. Collecting rings gives no proper reward in 2P but adds lives to the 1P counter, but no matter how many lives are lost in 2P these are not added up to the 1P counter. It's also worth mentioning that changes done in a level will remain so even after both characters die (rings will stay collected, obstacles will stay fallen, enemies will remain defeated and so on).
Beating all of Sonic's and Shadow's levels will unlock secondary skins based upon Phantasy Star Online, maybe based upon HUmar and (red and black) HUcast respectivelly. There're also alternate skins for Halloween and Christmas.
The attacks at each characters’ disposal are the same from normal playthrough plus Sonic Wind/Chaos Spear and two additional attacks, Speed Up (a small burst of speed) and Time Stop/Chaos Control (a ten second advantage in time) for Sonic/Shadow. These attacks can be triggered every twenty rings collected. If any of them dies, they spawn on the last Point Marker that the opponent went through and they are given a random attack as well. Additionally, if any dies by falling off the stage, they respawn with a puff of smoke.
Beating all of Sonic's and Shadow's levels with an A rank will unlock secondary characters for them, Amy and Metal Sonic, who play just the same but have no equivalent of Light Speed Dash. Metal Sonic uses its engine to thrust itself, so he hovers instead of running albeit it's able to step if moving very slowly.
The level is the same as Green Forest. There are no changes worthy noting, besides the Mystic Melody's path disappearance, the lack of balloons in the bungee jumping area and the rumbling area towards the end doesn't submerge, just changes level heights. The latter area doesn't rumble while Time Stop/Chaos Control are in effect either.
The level is the same as Radical Highway. Notable changes include no trail of rings leading to the Flame Ring upgrade, the trail of Beetles after the hexagon pillars in the middle at the Golden Bridge section after the second Point Marker is now done my a simple Mono Beetle and Spring Beetle while taking the lower route doesn't trigger the Blue Eagle nor does it end with a trail of Beetles but has a dash pannel instead, and finally a spring instead of a group of hexagonal pillars after the third Point Marker. This is the only level in the racing 2P that has invincibility and speed shoes item boxes/balloons.
The level is the same as Sky Rail. Notable changes include the lack of trail of Beetles leading up to the Ancient Light, the Mystic Melody trail of rings and the skulls not breathing fire at any point. This is the only racing level that has an extra-life item box but which has no purpose.