Sonic Advance 3: Part 31: Special Stage 2 (Blue Chaos Emerald)
Here's another Zone that I missed getting a Special Key in, so I had to redo an Act in Sunset Hill to get one for its Special Stage.
This also gives me an opportunity to show off more team combinations, and what moves my leader character has from it. When Tails is partnered with Knuckles, he loses the ability to fly and instead uses his twin tails to glide more like Knuckles.
Underwater, he replaces his doggy paddle with a breast stroke. He doesn't swim as vertically this way, but he does swim much more horizontally.
He also gets an Insta-Shield of his own and a huge Twister attack that leaves him dizzy if he uses it for too long.
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In Sunset Hill's Map will be the Blue Special Stage. It's just slightly harder to beat compared to the first one. Not only will you have bombs to dodge, but also Badniks, though these can be destroyed for extra Rings, if you want.
Once again, this Special Stage will need you to collect 80 Rings for Round 1, and then 160 for Round 2 before it gives you the Blue Chaos Emerald.