No, Zebrika may be fast, but he's frail and doesn't learn anything else but Nitro Charge and wild Bolt. And he will die very easily and his Attack stat isn't the best, so it won't be KOing too many things.
Low Tier
Meruba is severely underated! Well, he may have that awful Stealth Rock weakness and the fact that you get him at Lv.1 doesn't mean he should be at the bottom. He has an excellent Special Attack and Special Defense stat, with decent attack and a wonderful speed stat. But then again, he evolves at Lv.59, but the good news is that he has a vast movepool, so he can learn quite a few stuff.
Mid Tier
Dageki is underrated. He has sturdy, 125 base attack and 85 base speed. He can also learn Close Combat which is better than Superpower, and he learns more fighting type moves than Nageki by level-up. And even though he may have a little less Defense than Nageki, he still has a respectable 85/75/75.
High Tier
Yeah, you're kind of right. When Shimama first evolved, it pwned everything. I mean, it is fully evolved at lvl 27, while your other pokemon are stuck in their first or second. 100 base attack at that point in the game is really good, but gets worse as time goes on. It isn't low tier material though. Darumakka is all the way up in high tier, even though it evolves at level 35, and Hihidaruma has just crappy defenses (although its attack is insanely high). Plus that fire-typing is terrible defensively, while Zebraika has only one weakness. I still say that Zebraika should be in
Mid tier, because all the new pokemon evolve really late in this game.
Are you kidding me with the Meraruba stuff? It has horrendous stats all around. You call 50/55 good special stats, and 60 fast? Getting it at level 1 makes it even harder to level it up, as it will still be in this stage when you fight the elite four. Most people don't even get their pokemon to lvl 59 at that point. Its movepool is decent, at least from TMs, as it only learns fire, normal and bug type attacks by level up (and only every 10 levels too). At level 50, it will only have Nitro Charge, Bug Bite, and Double Edge. This thing is so much worse than Zebraika. Ulgamoth is great, but no one will have the patience to train a weak bug pokemon with a terrible typing, terrible stats, and terrible level up moves.
Low tier definitely, it deserves its spot as the second worst in game pokemon
Dageki is really good, since it has great attack and speed without even evolving. Plus, it easily destroys the normal type gym, as you get it right before.
High tier
I say munna should still be moved up, as level 37 isn't that bad compared to everything else in the generation evolving super late. Alternatively, you can evolve it as soon as you get the moon stone, sticking with psybeam (still good) until you get the TM on route 13.
Purotooga is really good. I fail to see why it is below Aaken. It has good abilities, good moves, and is bulky physically. If you didn't get Mijumaru/Oshawott (lol), Purotooga is your best option for a surf user. Shell Smash is what really makes it shine, as now it outspeeds everything and can hit both physically with aqua jet and crunch (when do you get the stone edge tm?), and specially with surf.
Mid-High tier
Mogurew is overrated. It is hard to train up to level 19, when it gets Dig, and doesn't evolve until level 31. Doryuuzu is a powerful pokemon,with swords dance and earthquake, but is pretty slow without a sandstorm going.
High tier
IDK about Gobitto, but it learns fly despite being a ground ghost type.