You're right, I don't like any of those except plachilla, no offense.Yes, I'm not good at naming things...
If I were to try it'd be like...
Tsutaja: Boarbor (Boa + Arbor)
Pokabu: Swire (Swine + Fire) [The last form should be named BOARUPTION]
Mijimaru: Wotter (Otter + ...Water)
Chiramii: Chinchild (Chinchilla + Child)
Munna: Pachidream (Pachiderm + Dream)
Gear: Gear
Mamepato: Pudgeon (Pudgy + Pidgeon)
Hihidaruma: Darumonkey (Daruma + Monkey)
Shimama: Zebrawatt (Zebra + Watt obviously, pretty lame but I think it sounds just fine)
Meguroko: Crookodile (Crook + Crocodile, I mean, it looks like a thief to me)
Zoroark's english name is practically confirmed to be Zoroark in both the US and Japan, so I'm guessing the same holds true for Zorua, Reshiram and Zekrom.