As I mentioned in my piece on Sultai Poision, the 25 point starting life total in Tiny Leaders makes alternate win conditions attractive. In particular, a 49 card library makes milling sound like a very viable win condition. Fetchlands are popular, drawing cards is always popular, and if your opponent keeps a seven card hand then you're only looking at getting rid of 42 cards!
42 is still, obviously, higher than 25, but the cards that mill compare much more favorably in this ratio than they do when you compare 53 to 20. Ambassador Laquatus is the leader that you could select if you wanted something in your command zone that actively contributed to your plan, but considering that Glimpse the Unthinkable, a veritable two-mana Lava Axe, is only available in blue/black that seems to be where the smart money is at. Unless we want a third color (we probably don't), Sygg, River Cutthroat is our only option.
Ultimately, the best deck is going to focus on efficiently milling with a few options as milling-mana-sinks. Glimpse the Unthinkable is great, Nephalia Drownyard is great, Sands of Delerium is slow. Here's where I landed on a list:
Having 25 life gives us a good amount of time to do nothing, but we do need to play a few cards that stop us from dying. Dimir Charm plays pretty well in Tiny Leaders, as it kills a very high percentage of the creatures. Countering a sorcery is reasonable value for two, and now and again you can use it to mill in your mill deck.
The card that probably looks most out of place here is Lotus Petal. In general, I think that Lotus Petal is awesome in a lot of Tiny Leaders decks. While you'll want more than three lands fairly often, it won't often matter that you have a ton of mana on a given turn. Lotus Petal allows you to do something like power out Ashiok, Nightmare Weaver a turn early, and is also a free way to power up Brain Freeze.
Some might consider not playing Duskmantle Guildmage and Mindcrank as a glaring omission, but I really dislike their inclusion. You already don't play many targets for removal, and Mindcrank doesn't really do anything in this deck on its own. Having a combo win is nice, but it's difficult to justify playing a combo with weak pieces in a deck that otherwise spends a lot of time casting cards that count as functional mulligans until you actually win the game.