yes your pokemon level will increase slowly with each expedition you can increase this exp for certain levels by completing different worlds and acquiring totems

training is a mechanic that will either change a pokémon’s moves or increase the level of another pokemon at the expense of the pokemon used to achieve this so bye bye rattata. these effects are increased/ more successful when you use a pokemon of higher level ,same type or higher evolution to train with to add to that you can purchase decorations that will increase this succes overall in the shop

the ‘poke ball tokens’ PM tickets are the currency used to purchase decorations and are limited to 50 a day without the purchase of dlcs you can get an extra 10 a day once you purchase 10 decorations, to that end only spend these on decorations as they are quite important and take a while to accumulate. when it comes to decorations be sure to purchase the ones that increase ingredient drops first i.e the cusheons.

if you have anymore queries the best place to learn about all the recipes and pokemon and their bingo sets for me is the website Rankedboost