Only Connect Group 10

Pokemon with 4 of that letter in their names
U - only Pyukumuku, a water type from Gen 7 ( https://bulbapedia.bulbagarden.net/wiki/Pyukumuku_(Pokémon) )
A - Stakataka, a rock/steel type from Gen 7 ( https://bulbapedia.bulbagarden.net/wiki/Stakataka_(Pokémon) ) and Alakazam
O - Hoothoot and Sudowoodo from Gen 2
E - Eevee
Steenee, a grass type from Gen 7 ( https://bulbapedia.bulbagarden.net/wiki/Steenee_(Pokémon) )
Celesteela, a steel/flying type from Gen 7 ( https://bulbapedia.bulbagarden.net/wiki/Celesteela_(Pokémon) )
Beheeyem, a psychic type from Gen 5 ( https://bulbapedia.bulbagarden.net/wiki/Beheeyem_(Pokémon) )