Best toy breed training treats.

My suggestion is tiny bits of chicken wieners. Cut each wiener length-wise into 4, then slice those 'slivers' into tidbits as small as practical. About half the size of a pencil eraser or thereabouts, if possible.

You can cut up an entire pack this way, store the majority in your freezer, and keep a small supply of thawed pieces on hand to use as required.

Yes, small treats to provide a smell and a taste. When training, you don't want to have the dog spend time chewing or snuffling around on the floor looking for lost bits. Keep training quick, upbeat and don't make the sessions more than about 5-10 minutes. You can do multiple sessions during the day.

Poodles are very smart. You could probably work on several commands while doing the potty train. For instance some basic commands like, Sit, Heel, Stop, Drop, Pass, Look, Stay.........
Focus on control commands first, then later you can begin the tricks.

Depending on how much he likes his food, sometimes pieces of kibble are good enough treats.

But otherwise, I agree with using small bits of cooked and/or dried meats (plain chicken breast is great), cheese, or sausage (nothing with a lot of spices or salt!). Our favorite store-bought treats are freeze-dried pure meat or organ, here, though sometimes they can be hard to break up into small bits for our small dogs.

With the tiny guys especially, remember to factor in treats to their daily food intake. I believe you can replace up to 25% of their food with treats, especially if you're using something relatively healthy like pure meat. But little dogs pack on weight fast, so just take care that he's not getting too many calories.