The problem with using the Sonic cast is the sheer number of unique characters, many of the cards you have designed have rules text that prevents more than one of them being in play.
On that note, you should consider having a rule akin to the Legend rule from MtG, which states that if a card's class is 'Legend' or 'Legendary', a player may only have one of that card in play. I forget the exact rules around that.
MtG current rules: Whenever two or more legendary permanents with the same name are in play at the same time, both are put into the graveyard as a state-based effect.
And if you look at, say, my Sonic card (RFP n00b), it says "You can't play Sonic the Hedgehog ... if another card named Sonic the Hedgehog is in play."
CF has some decent ideas. I was considering a similar effect, but maybe lifting the character restriction on Light Shoes/Air Necklace, because otherwise they'd be virtually useless. (Also: Ancient Light gives light attack, not light shoes.) Additionally, they'll probably just be permanent effects. Chaos Powers are something to consider too. (I like your concept for Chaos Emeralds too. I might tweak it a little bit, but 'tis cool.) :D
I also had a slightly different idea for Shadow that I was going to implement. It probably was going to involve Chaos Control rather than Chaos Blast though; otherwise, it's pretty close to Gamma.
RPG: srsly I want the game to be balanced not insanely stupid. >_>
Also I'm going to post what I've worked out so far as for rules/gameplay:
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Object: Get one of your characters/robots to the capsule (your opponent)! Get one of your characters all the way across the board, amidst your opponent's obstacles and his own characters, while stopping your opponent from doing the same!
Alternately: If you run out of cards in your deck, you lose. This is called "Time Over."
CARD TYPES:
CHARACTER (Tentative name) - Contains not only mainstream characters but also animals and robots that either defend your capsule or attack your opponent. Character cards have the following stats:
-Cost: How many rings you must spend for it to come into play.
-Speed: How many tiles a character can move in one turn. Note: A character can't move the turn it comes into play.
-Ring: How many rings a character gains each turn it's in play. Rings prevent a character from being sent to the Scrap Heap when hit. If a character with rings is attacked, it loses all of its rings. If it's attacked with no rings, it dies and is sent to the Scrap Heap. (Note: A character doesn't gain rings if it attacks during its turn.)
-Abilities: Any abilities the character has, if any. For example, Sonic can't be put into play if you have any robots in play. Tails can avoid attacks occasionally by flying.
-Recollect: If a character doesn't move the turn after it's hit, this is the maximum number of rings it can recollect after losing them.
-Difficulty: How hard it is to destroy a character. See below.
-Type: What kind of character the card is. For example, it could be a Hero, Animal, Robot, or almost anything else.
EFFECT - Cards that give an effect to a character (yours or your opponent's) or a set of tiles on the board. The card always tells what it does here. For example, shields protect your character's rings from one hit. Effect cards have the following stats:
-Cost: How many rings you must spend for it to come into play.
-Effect: What the Effect card does.
OBSTACLE - A card that you can play on your opponent's turn to stop an opposing character's progress. Spikes, loops, and pitfalls fall under this category. Obstacle cards have the following stats:
-Cost: How many rings you must spend for it to come into play.
-Effect: What the Obstacle card does.
BOSS - A special type of card that you can only have in your deck if you have lost a game during a match. A boss blocks the opponent from getting to you and can attack characters, but it can't move. If a Boss card is destroyed by an attack, you lose the game. A player can't have more than one boss card in play at any time. Boss cards have the following stats:
-Cost: How many rings you must spend for it to come into play.
-Armor: How many times a boss must be attacked before it is destroyed.
-Effects: Any special effects that the Boss card has, if any.
GAME STRUCTURE
1. Flip a coin to see who goes first.
2. Each player gains 5 Rings.
3. Each player draws 6 cards from their deck to form their hand. If a player doesn't like his or her hand, they may pay one ring to get a new hand (of 6 cards). Remember, there aren't many cards you can play that cost 0 rings!
4. Begin the game. For each player's first turn, they don't gain any rings.
5. The player whose turn it is draws a card.
6. The player whose turn it is may spend rings to play Character, Effect, and Boss cards.
7. The player whose turn it is may move any or all of his or her Characters in play a number of tiles equal to its speed. (A character can't move if it just came into play!) (NOTE: If another character is blocking its way, the moving character must stop and attack it. It can't move after attacking.)
8. If two characters are in the same tile, they attack each other.
- Roll a 6-sided die. If the attacker's roll is greater than the defender's Difficulty, the attacker is considered hit (see below). Both players do this for each Character being attacked.
- If the roll is less than the defender's difficulty, the attack fails and that character loses all its rings. It then must go back one tile. (If it has no rings before it attacked, put it in the Scrap Heap instead.) If a character is hit, it also loses all its rings and goes back one tile. (It goes to the Scrap Heap instead if it already had no rings.)
9. The player whose turn it is gains 2 rings plus one ring for each character that player has in play. (This doesn't happen on a player's first turn.)
10.If the player whose turn it is has more than 6 cards in his or her hand, that player must discard cards until he or she has 6 cards in hand.
11.The turn passes to the next player.
12. Repeat Steps 5-11 until a character reaches an opponent's Capsule (deck).
13. The player whose capsule was reached may add Boss cards to his or her deck (and may replace other cards in his or her deck with them).
14. Repeat steps 2-13 until a player has won 2 games. That player wins the match. (Whomever lost the last game goes first.)
15. If a player wins 2 games, they win the match!
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More cards/more input is appreciated. Again I'm probably considering adding Chaos Powers. I just need to twist things around and turn them into rule-ish things. :o
I like the lol value of Froggy. >_>
I'd probably lift the play restrictions on Chaos/Chaos6/Froggy/SuperSonic though. (At least change Super Sonic's.)