If damage that can't be prevented is dealt to Bloatfly Swarm, you still remove that many +1/+1 counters from it, and you still give each player a rad counter for each +1/+1 counter removed this way
With this kind of deck, it's important to keep a card advantage so you can continuously increase your board state and put as much pressure on your opponent as possible
You need the right ones, and the answer to what is "right" is going to vary significantly depending on your strategy and personal preference
So, Im going to potentially teach you some new vocabulary and hopefully give you a little more insight into how live service games like Pokmon TCG Pocket work
Some deck leaders have unique abilities based on their type and rank, such as increasing and decreasing nearby monsters' points, increasing life points, and moving an additional space on the field