A bunch of random ideas (some nerfed versions of broken cards, a universal OTK counter, and an alt win that's hopefully not stupid)

[Zowayix]

Heavily nerfed Delinquent Duo:
Normal Spell
[i]Your opponent selects 1 card in their hand and chooses whether to return it to the top of their Deck or send it to the Graveyard.[/i]
Still overpowered, or not?

"Good" (?) alt win based on the same principle as Vennominaga:
Continuous Spell
[i]Once per turn: You can Tribute 1 Level 11 or higher monster [s] or 1 "Larvae Moth" [size=1](trolololol)[/size][/s] you control: put 1 counter on this card. When there are 3 counters on this card: you win the Duel. Once per turn, when a card effect is activated: you can make this card unaffected by card effects.[/i]
Basically, level 11+ monsters are very difficult to Summon, so you would normally be able to win anyway with just those 3 monsters that you Tributed. Also you must spend at least 3 turns with this card out to use it; no FTK loops possible.

Nerfed Change of Heart:
Normal Spell
[i]Take control of 1 Normal Monster your opponent controls until the End Phase.[/i]
How many people run Normal Monsters outside of Rescue Rabbit? And in the case of Rabbit, the monsters don't even stick around during the opponent's turn for them to use this.

Stronger version of Ancient Leaf:
Normal Spell
[i]Pay Life Points until you have 8000 left; draw 1 card for each multiple of 1000 Life Points paid.[/i]
I posted this earlier but didn't get many comments. Is it too strong with Aegis of Gaia?

Anime Card of Sanctity, but much less overpowered:
Normal Spell
[i]Activate only during your Main Phase 2. Draw cards until the total number of cards in your hand and on your side of the field totals 6, and your opponent draws 6 cards.[/i]
No setting your hand to net a +5, unless your field is completely empty. Your opponent gets the maximum benefit of the card no matter what. Also, you can't attack in the turn this card was activated, so no FTK/OTK possibilities.

Almost-universal OTK stopper:
Quick-Play Spell
[i]You can activate this card by banishing it from your Deck or Graveyard. If your Life Points were at least 8000 at the beginning of this turn, and they now would become 0: Your Life Points become 4000 instead, and cannot become anything other than 4000 until the start of the next turn.[/i]
(You can still activate this card normally from your hand or field, it just won't be banished.) If your opponent is about to land the final blow of an FTK/OTK, just drop this to stop it. FTKs/OTKs are inherently bad for the game; I see nothing wrong with making a universal preventer.

[.Exa]

Delinquent Duo:
Still seems a tad bit OP (my personal opinion) just because, even if your opponent selects, they still lose a card for the turn. Although, Gishkis might benefit from the first effect. [s]Maybe put the second on on discard, so it could go with DWs and make it less powered.[/s] Nah, DWs are good as is.

Alt win:
Nice. Maybe: Tribute 1 "Perfectly Ultimate Great Moth: You win the Duel."
lulz

Change of Heart:
Fair enough, no special comments.

Ancient Leaf:
Not too strong in any way, although could be lulzy with Aegis of Gaia and Golden Ladybug.

Card of Sanctity:
Good, benefits both players without being overpowered, and even puts you in a minus situation, whenever you play it, except when both players have no cards in their hands, but even then it's a +0 so it's good.

OTK stopper:
Would say OP, but it's not, and we really need something to stop all those OTKs, so there.

Overall:
9.1/10

Based on no specific criteria, but just on how much I like the cards, and how much is the OCG correct.