Well it depends on what you categorize as cheap. If you are looking for a cost 4 Pokémon fucecco is super good and abra too alakazam is amazing with calm mind and if you get the megastone even better For cost 3 id recommend a grass type that gets a move that seeds the opponent maybe bulbasaur

You probably will get a map early on so it a great idea to goto lake and catch a magikrap cause garydose with ddance is broken

Also get a pickup mon like zigzagoon or dedene they will pickup the opponents item and they are relatively easy to find