The blue dressed one is Popo, the pink dressed one is Nana, together they are the Ice Climbers! They are the only character which fight together and so they are vary strange to master. If Nana dies, Popo won't die too but he will be very weaker. They are Twin characters and their main element is Cold.
Standard Special: Ice Shot. Popo and Nana throw an ice block each. A block inflicts 2% of damage.
Side Special: Squall Hammer. Popo and Nana rotate together three times each. A spin inflicts 3% of damage.
Up Special: Belay. Popo launches Nana who has a rope and she launches Popo higher. if Nana has dead, Popo will do a little jump.
Down Special: Blizzard. Popo and Nana shot a little blizzard each which inflicts 9% of damage each. If used on ground, the Ice Climbers will shot the blizzards in different directions, if used on air, the blizzards will have the same direction.
Final Smash: Iceberg. The Ice Climbers evocate an iceberg into the stage for 15 seconds. A second touching the iceberg inflicts 2% of damage. The Ice Climbers won't be hurt.
Meet them in Story Mode or complete Event 14: Colder than Ice.