These loops are long-term wincons. They will win you the game by ensuring your opponent decks out first, provided:
You're not under any pressure (say you're playing a control/stall deck, and have neutralized all your opponent's attacking options).
Your opponent isn't playing any anti-deck out loops of their own.
Your opponent isn't playing mill (because that can disrupt the loop).
Play the recycling card (usually Pal Pad) to shuffle cards back into your deck, then use Electromagnetic Sonar to get the recycling card back.
Bench Abra, attach Jet Energy to it to send it into the Active Spot, then use Teleporter to shuffle both cards into your deck.
You need at least a 3-2 Dudunsparce line to do this. Start with a Dunsparce (ready to evolve) and Dudunsparce Benched. Have Dunsparce in hand, and your deck down to only 1 card, which is a Dudunsparce. (Alternatively, you may have Dudunsparce in hand and Dunsparce in deck instead.)
Use Run Away Draw. Now your hand will contain Dunsparce + Dudunsparce, and your deck will have the same 2 cards in a random order. Evolve the Benched Dunsparce and play the other Dunsparce to the Bench. On your next turn, you draw a card, and are back where you started.
An interesting thing to note is that having an anti-deck out loop is how Great Tusk Mill actually wins the game. Great Tusk can mill the opponent, but it also reduces its own deck size with Explorer's Guidance (-6 cards) and Professor Sada's Vitality (-3 cards), which it must play in order to get the bonus on Land Collapse. What it's doing when it mills is slowly removing the opponent's outs — for example, it can mill some Energy and use Handheld Fan to deal with the rest of the Energy that didn't get milled, or mill all the opponent's Stadiums so Neutralization Zone sticks. In order to win after establishing board control, it must have a way to make the opponent deck out first, which means playing a high count of recycling cards (2 Pal Pad + 2 Super Rod), and incorporating an anti-deck out loop.