These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Sonic Battle
Character Tiers: Two tiers in particular are such outliers that it basically becomes:
Cream's heal restores the Ichikoro Gauge by ridiculous amounts. It's not so bad as health goes, either.
Tails and Rouge have Set supers that track the opponent. When charged to instant kill, they remove an entire plane from where one can safely stand before dying.
Tails and Rouge also have midair attacks can loop an airborne opponent while keeping both of them suspended, preventing them from being able to block by touching ground, until the opponent is dead.
Emerl himself ends up being absurdly powerful, able to floor any given opponent in a single combo and pursuit attack.
Emerl's Character Combo supers guaranteed to kill the opponent if every hit connects (except Chaos in Story Mode). Worse, they don't count as any particular type of special attack (Shot/Power/Set), meaning that even if your opponent sets their guard to block Power-type attacks (what they're assigned to), they'll still hit. They can also be charged with the Ichikoro meter so only one hit needs to connect.
Emerl can be a game breaker from the beginning. Without any skills. The actual spin dash part of Sonic's Shot skills don't have a Shot/Power/Set value assigned to them, so either the actual skill or the failed basic version Emerl starts with (which doesn't include the shot at all) can kill anyone with a charge Ichikoro meter. Similarly, his basic Ground Set can lock an opponent in hitstun if mashed often enough.
Between movement capabilities that allow him to run circles around his opponents and powerful attacks that can quickly beat his opponents, Shadow is one of the best of the "regular" characters. This was supposed to be balanced by his weak defense and healing abilities, only Shadow is so fast that he'll almost never be in battle unless he wants to.
Repeatedly press B at a constant beat with Amy. Do it slow enough so you don't finish her jab combo, but fast enough that you can punch again before the opponent's lag is done and they can break free. Amy can frame lock anyone.
That One Attack: For many it's Gamma's Recovery Mode. He does spell it out for you, however, and after minimal practice it should be easy to be able to guard it. The high power makes it give you a LOT of meter. Eggman has a similar one, except it comes out immediately when he's K.O.ed.
Eggman can be one given his missile spam and tendency to explode when knocked out.
The fight between Rogue and Team Sonic at the end of the third chapter. Being forced to fight three against one is just torturous unless you stay in the air and pick them off slowly.
The Guard Robots as Knuckles. At first it's not bad, with just one. Then you fight two. Then three. No breaks in between. If you're not good with Knuckles, this is a nightmare.
Any Phis copying Gamma, especially late-game.
Ditto with the Guard robots. Since they don't talk, it's difficult to dodge Gamma's Recovery Mode with no audible cue.
The fight with Rouge where Emerl has to get 10 KOs without using any special moves.
The Sonic and Shadow fight before the final chapter. Sonic and Shadow, who have huge handicaps to make them competent fighters, against an Emerl player who's still trying to find the perfect moveset to stick with. Not even the unlockable combo attacks will guarantee a kill.
The first fight against Knuckles as Emerl can be this. At this point of the game, you'll have very few skill points for Emerl to use many skill cards for attacks. Many of Emerl's attacks will be slow and weak. And depending on how you arranged your skill cards, he won't be able to jump that high, or his movement could be incredibly slow. This definitely makes things a challenge when fighting the powerful and fairly quick Knuckles.