Bonding

Every pokemon has bonding partners which can improve their stats (sp.atk, p.atk, sp.def, p.def, hp or speed) when they reach certain requirements.

How it works
In order to receive the bonding bonus you need to have the bonding slot unlocked, some epic pokemon or pokemon which can't evolve have all their bonding slots open since level 1, but others like Charmander have to evolve in order to unlock the bonding slots. Once you have the bonding slots available then you will need to have the bonding pokemon or any pokemon that is part of his evolution chain.

After this you will need to improve a certain aspect of the bonding pokemon in order to receive the stats improve on your base pokemon. You will be asked to improve one of three attributes: Each bond has 5 levels and they stack, meaning that if you unlock the 5th level you will receive the benefit of that level and the 4 previous levels too.
 * You will be asked to improve the bonding pokemon's level.
 * You will be asked to improve the bonding pokemon's friendship level.
 * You will be asked to improve the bonding pokemon's fusion level.

Bonding List
Here are all the bondings for each pokemon, the tables have the following information.

Fire Pokemon

 * Charmander / Charmeleon / Charizard / Mega Charizard X / Mega Charizard Y
 * Torchic / Combusken / Blaziken / Mega Blaziken
 * Houndour / Houndoom / Mega Houndoom
 * Groudon / Origin Groudon
 * Volcanion
 * Victini
 * Moltres
 * Ho-oh
 * Reshiram
 * Entei
 * Magby / Magmar / Magmortar
 * Larvesta / Volcarona
 * Torkoal