Friendship Items in Magikarp Jump allow you to befriend Support Pokemon and get their help, both at the pond and during competitions at the League. You can purchase these at the Diamond Shop, but some of them can only be earned by completing Leagues.
Magikarpa 5-25% JP boost. Some of the Support Pokemon can be upgraded, which enhances their effects at the pond, with Support Candy. Get Support Candy as a shopping bonus by purchasing Training and Berry upgrades, or by winning League battles.
Editlist of friendship items and Support pokemon
The best Friendship Items are arguably the ones you get for free by conquering Leagues. Piplup, who you befriend after defeating the Quick League, restores a Training Point every one and a half hours! That’s hard to beat.
Otherwise, the purchasable Friendship Items all have their own merits. Pick your favorite and have no regrets!
Also consider, Slowpoke looks like the best option at first glance. However, it restores the skill for just one Support Pokemon every 12 hours. This would be decent to combo with Charizard, granting you two great items every 12 hours. To time it correctly, just make sure only Charizard has used its skill, then use Slowpoke, guaranteeing it will restore Charizard’s skill again.
Rowlet is another great early pick because it grants coins, which are easy to earn, but having more will allow you to upgrade more food and training items. Rowlet’s skill cooldown is one of the shorter cooldowns for the higher priced Friendship items (aside from Snorlax).