Could I make a case for Diggersby? You get it pretty early, access to EQ, Quick attack and Strength, overall pretty powerful. Plus, unlike Azumarril, you don't have to be lucky to get it. (Although Azu is a flatout monster. Solaris ain't got shit on him) Mamo is great, too, but you'll have to breed Icicle Crash from a Beartic (level 37, iirc) for optimal results. For Roserade, you'll have to do some serious breeding to get the best results. You might want to consider Archeop, too. That thing is very strong (Healing items work around Defeatist), although EQ requires episode hopping. If you do the Spinel museum sidequest in time, you can get it before facing Serra, iirc. Flygon is noticeably weaker, but has a stronger EQ and learns proper coverage through level-up. (Superpower/EQ/Rock Slide/Dragon Claw e.g.) You can get it around the same time. Crobat can be nice, too, plus you can choose between a physical or a special set (I prefer the former). Besides Acrobatics gets boosted in some future fields for you. I'm not sure how well Cofagrigus does after Serra (a particular boss completely counters it), but it is a fine tank, in particular to physical behemoths. This game made me really like him, seeing how easily it can shrug off hits, cripple the opponent, and then just beat it to pulp. Prankster mons can always be helpful, especially Murkrow (Rain Dance, Perish Song...), so kepping one for emergencies can be recommended. Out of your suggestions, Noivern, Staraptor and Crawdaunt seem the better options to me. (Noivern gets Super Fang, too. Could be handy)