Before I delve into the subject matter of how to win big when going second I'll first discuss the fundamental tenants to playing a pure drop pod army. I spent over a month designing my army list and solicited advice from other tournament players whom I consider top Space Marine players. I also did a lot of research on the Internet to see what other people had to say. I think drop pod armies are stronger now with the new Space Marine codex based upon my findings.
The drop pod army is the ultimate alpha strike army and only Tau have the right tools to effectively deal with it (i.e., massive amounts of intercepting units). Versus Tau your opponent must decide whether to nova charge their Riptides for Ripple Fire or the 3++ save. If they go for Ripple Fire then alpha strike them and their Broadsides. If they opt for the 3++ save then alpha strike their troops (assuming they are on the table).
CHAPTER SPECIFIC
Here are what the experts said are the top Chapters to choose from when designing a drop pod army. They are presented alphabetically, not in a ranking of strength:
Crimson Fists
The main key here is the Chapter Master Pedro Kantor unlocks Sternguard as scoring units and they are one of the ultimate units for any drop pod army. Based upon my research it's best to field five man squads with all combi weapons and a heavy flamer. They have the option to come in during the second or third wave either crushing strong enemy units left out to dry such as Riptides and Wraithknights or torching exposed weak xenos troops—outflanking Kroot, eldar jetbikes or pulse bomb Fire Warriors. In my mind it's a one to one trade for each enemy scoring unit you eliminate in objective based missions. Tau players will be forced to decide whether they want to protect their Riptides and Broadsides or their troops... It's a really tough decision.
Salamanders
Again you'll want to take the special character, Vulkan He'stan since he unlocks master crafted melta weapons. Salamander Sternguard are arguably the best of any Chapter when equipped with these weapons and you might want to field larger squads than the bare minimum to take better advantage.
Ultramarines
I personally consider this the best Chapter due to their Chapter Tactics plus their two special characters Marneus Calgar and Tigerius. Both of these special characters are awesome in their own rights so it's total win-win. Marneus let's them double down on their Chapter Tactics and Tigerius' Warlord Trait is perfect for drop podding Space Marines.
ALLIED SPACE WOLVES
Space Wolves are your best choice for an ally just as Ultramarines are the best choice for your primary detachment. Remember that Space Marines are able to ally within their own codex so you have the potential for two allies under 2000 points! You can also field two Space Wolf HQ as an ally - not that it's necessary for a competitive build - but still it's there. The two optimal units are a Rune Priest or two attached to a squad of Grey Hunters. You can either go for double JAWS versus monstrous creature heavy armies such as Triptide Tau or Prescience to buff your drop units. Space Wolves are still very strong in a drop pod army and can best utilize their base raw strengths.
Okay so we have covered which Chapters are the best so let's now delve into some of the fundamental tactics and strategies for drop pod armies.
6" Disembark
It used to be you could only disembark 2" out of a drop pod, now it's 6"... That's huge! Suppose you are up against an IG blob walled off behind an Aegis Defense Line. If possible land on top of terrain so you can disembark shooting over the defense line to effectively ignore cover. Versus Tau disembark the Marines 1" away from an enemy unit so they can't drop their Riptides' pie plates. The 6" disembark out of a drop pod is one of the best things to happen for drop pod armies. Versus Eldar drop in behind their wave serpents and smoke them firing with complete impunity into rear armor.
Honor Guard, Tigerius and Forewarning
Honor Guard got a lot cheaper (another blessing for Space Marines) plus they have artificer armor for the 2+ save. Tigerius can reliably get the Divination psychic power Forewarning blessing this squad and himself with the 4++ invulnerable save. They come stock with bolters thus making them more viable as a drop squad. They also are an excellent retinue for Marneus Calgar as intended. Every army needs some muscle too.
Okay that's all for now.