The batteries don’t always swap between planes, generally the bigger Simple Series planes keep similar sizes, a 2200mah 3s 40C will do most of those. The Tiny Trainer uses smaller packs, mine were about $9 each so it was easy to have lots.
Pick a starter plane, fly it until it’s destroyed, then salvage the electronics and build another. That is better than trying to move between multiple planes. Things like servos are bonded into the airframe, you can’t easily switch them.