Question: I'm a very new player to the Pokemon TCG, and have picked up two themed decks to play with ([Ultra Prism](https://www.pokemon.com/us/pokemon-tcg/sun-moon-ultra-prism/theme-decks/)).

So far in my experience however it seems that if one player gets their active Pokemon to its final evolution (for example [Empoleon](https://www.pokemon.com/us/pokemon-tcg/pokemon-cards/sm-series/sm5/34/)) before the other player, then that player has a massive advantage, and is able to one shot all of the opponent's Pokemon before they can do enough damage to knock out the evolved Pokemon.

Is there a strategy for countering this? It can turn a game very one sided very quickly.

Answer: 
Overall, strategies include a switch, sleep stun or paralyze, and energy discard. Look through your decks carefully. Many pokemon as well as trainer cards can use one of these techniques. Theme decks usually have some decent trainer cards. It's your job to decide when to use them. In a little more detail:

**Switch:** Switch an opponent's benched pokemon with their active one. Swap that basic low HP pokemon on their bench with their evolution. Guzma is a (currently active) supporter card which does this quite well, although it also requires the player to switch their active pokemon so a little planning is required. Pokemon Catcher is an item card that has a 50-50 chance (coin flip) of doing a switch. This technique requires your opponent to have a benched pokemon.

**Sleep, stun or paralyze:** Several pokemon have attacks that cause these effects. This prevents the one-shot kill and lets you get some damage in. The opponent can clear the condition with trainer cards (Pokemon Center Lady).

**Discard Energy:** There are both trainer cards and pokemon attacks which discard energy from the opponent's active pokemon. If they don't have energy, they can't attack. 

I would recommend downloading the "Card Dex" app (made by Pokemon Int.) and look at some different item cards.
Other answers provide good strategies. I will try to provide additional info and some other strategies and cards that can help with that.

1. As [@TomYumGuy wrote](https://boardgames.stackexchange.com/a/48534/22542) you could **sacrifice** some pokemon while preparing your defeater on bench. There are trainer cards that can help with this like [Raihan](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/ss-series/swsh7/152/):

> 
> You can play this card only if any of your Pokémon were Knocked Out
> during your opponent’s last turn. Attach a basic Energy card from your
> discard pile to 1 of your Pokémon. If you do, search your deck for a
> card and put it into your hand. Then, shuffle your deck.
> 
> 
> 

2. One more option is to buy time with **pokemon/attack that prevents future damage** to it, for example [Shelgon](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/ss-series/swsh7/108/) - Hard Roll:

> 
> Flip a coin. If heads, during your opponent’s next turn, prevent all
> damage from and effects of attacks done to this Pokémon.
> 
> 
> 

[Diglett](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/ss-series/swsh6/76/) - Dig or [Pikachu](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/xy-series/xy8/48/) - Agility.

3. There are some pokemon/attacks with advantage against evolution pokemon like [Hitmonchan](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/ss-series/swsh7/81/) - Clean Hit:

> 
> If your opponent’s Active Pokémon is an Evolution Pokémon, this attack
> does 50 more damage.
> 
> 
> 

4. It is also possible to **devolve the pokemon**, f.e. [Golurk](https://www.pokemon.com/uk/pokemon-tcg/pokemon-cards/bw-series/bw6/59/) - Devolution Punch:

> 
> Devolve the Defending Pokémon and put the highest Stage Evolution card
> on it into your opponent's hand.
> 
> 
> 

Devolved pokemon might not have enough HP left and be knocked out!