I think you are being a bit mean there, In my opinion cubchoo, numel and seel should all be a tier higher. And I would also like to reserve the descriptions for these three pokemon, I have used all three before (suprisingly all on different play-throughs!)
Numel - Mid
Availability
They are all over the place in reversal mountain, and numel itself is extremely easy to encounter. Also, you can find Camerupt, the evolved form of Numel, in the wild as well in reversal mountain, and it's pretty much as common as numel, which is pretty darn common.
Stats
Defensively, Camerupt is not all that great; you wouldn't exactly call him frail though. However, just look at his attack stats! 100 physical 105 special, which is just awesome!
Movepool:
Well, Camerupt's movepool has it highs and lows - mainly highs. I mean, he comes with earth power, which is obviously amazing, but without help of a heart scale or move tutor it doesn't get it's first fire attack until level 55! If you have a heart scale, then I don't think there will be a more important thing for you to use it on than Camerupt's lava plume! Aside from that though, is yawn which can help in some important fights, rock slide (which you may as well have used a tm for if you wanted it) which is always great in double battles and for coverage, but also fissure right at the end, and with Camerupt's unfortunately terrible speed you can use the scope lense with for a 50/50 chance of a OHKO, which aren't that bad, let's be honest!
Major Battles:
Zinzolin - lacunosa town: Great! He only has pokemon weak to rock or fire (but you will have to use rock slide, unless you are level 55 :P)
Drayden: He can yawn here, but besides that...
Shadow triad: Earth power = gg
Marlon: Yeah.. uh... I think you know the answer to this... (if only he had mantine regular mode)
Plasma frigate, first visit: Yep, once again, brilliant! About 70% are ice or ground pokemon!
Plasma frigate, second visit: /\
Colress: Complete godsend, give it a lum berry or the berry that heals paralysis and it just wrecks the sturdy magnemite, and then past that you're all good except for beheeyem.
Kyurem-W: Rock slide is amazing on Kyurem, so yeah. ALso camerupt resists both of it's STABs!
Grimsley: Anything takes out Liepard, and he is pretty good on Scrafty, but really you should have better. Stay away from Krookodile, but Bisharp is so easy with Camerupt!
Shauntal: Great on Drifblim and Chandelure, and he could be handy against Cofagrigus because since it is fire type it absorbs the will-o-wisp that could otherwise cripple one of your pokemon until you heal it! Stay away from Golurk.
Caitlin: There is a brilliant strategy you can use with Caitlin; yawn HER musharna while she yawns you, then curse. Keep cursing until you fall asleep, wake yourself up with an item and then curse until musharna wakes up. It can only attack you with dream eater as his other attack is charge beam! Then go on and sweep the rest of her team with earthquake and then a rock slide/fire attack for her sigilyph! Works incredibly well, trust me, I did it.
Marshal: The only super-effective hit that marshal has on camerupt is throh's bulldoze - but it's not quite as simple as that! Conkeldurr is a complete powerhouse with it's hammer arm, and poor camerupt (to be fair, my skarmory couldn't even survive one! :P) can't do anything to survive a hammer arm! It's too slow too bring in after conkeldurr has used it a few times and deal a blow as well! So yeah, you might be able to take out the frail mienshao, but besides that this is a no-go.
Iris: EQ Aggron, it almost always autotomizes first turn it is in so it gives you a free turn to EQ. It can also be pretty good Archeops, but besides that, it's not all that great.
Additional comments:
Make sure you get solid rock camerupt.