I regret making this post
In the 'useless pokemon-o-meter', Gen 5 ranks up with Gen 3 for introducing the most useful Pokemon. Granted there a few awful ones like every generation, but we aren't swimming in them like Gen 4.
Cyrognal is a decent special wall, however it's defence cripples it against all physical attacks. Plus, the Ice typing gives all the weaknesses towards the most common physical attackers.
Liepard is just a poor man's Mightyena, a already rarely used Pokemon. It's about as frail as toilet paper.
The simi pokemon are awful too, and are outclassed by almost all of their rivals. Horrible designs as well.
The worst of all of them is Archeops. Defeatist basically makes a great looking attacker turn into a hit and run machine, plus it's awful defences basically makes it impossible to do anything to fast and powerful opponents (very common in-game).