Archeops is great in certain situations, but I'd be a bit wary about using it in-game. Archeops is pretty much the epitome of a glass cannon - it has a MONSTER Attack and good Speed, but its defenses are poor. Even more problematic is its ability, which cripples it should its HP drop below 50%. If it can dish out an OHKO, it's great, but if it takes a few hits, it really becomes much less useful.
To that end, Archeops is less easy to use, while Carracosta is a bit moreso. However, Archeops can certainly deal massive damage if used correctly.