Take a max-happiness Pokémon to Dr. Footstep and he'll tell you your 'mon's innermost feelings about you. They're usually quite touching and cute, especially if it's a "scary" Pokémon (like a Haunter or a Darkrai), or a "slow" Pokémon (like a Bibarel) that's grown sufficiently fond of you.
Most Pokémon: "<Name> is...a remarkable human and Trainer. That I can always perform the best any <Pokémon species> possibly can...I attribute that entirely to my partner <name>. When we travel, I can see wild Pokémon eying us enviously..."
Scary Pokémon: "There are no Pokémon that dislike humans... Only humans that dislike Pokémon... We <Pokémon species> are especially shunned... But <name> always treats me as a friend and partner..."
Slow Pokémon: "Hnurrr... Me? Uhm... Other Pokémon, they say to me... "You're not thinking, are you?" How insulting they should say so. It isn't true what they say. Think, think, think, I do that. All the time, I think hard how to help <name>. I concentrate! Hnurrr..."
Other Pokémon: "If I said there can be friendship between Pokémon and people, will <Pokémon species>'s friends understand? But if you see <Name> and <Pokémon species>, you will understand. Because <name> and <Pokémon species> are friends!"