CP or combat power is the strength your Pokémon has in battle. You can naturally increase the CP by evolving it which will also increase its HP or health. However with evolution also comes a totally new set of skills so if you like the skills your Pokémon has but want a higher CP, power it up instead of evolving it. Be careful though as powering up uses both stardust and candy while evolving only uses candy. Pick and choose which you prefer to do wisely. Another way to gain a higher CP for your Pokémon is to level up your trainer. Leveling up the trainer will give a slight increase to the Pokémon’s CP but will also allow you to catch higher CP Pokémon in the wild.