LANING:
During laning phase, if you have the stronger match-up, make sure to poke with autos and your Q. While laning in an unfavorable match up, try the tanky build and focus on protecting your ADC while they farm up for late game.

As Rakan your job is peel and engage so make sure to have your W ready to go in on pushed up laners when getting ganked or diving the enemy, or to get out of sticky situations when you cant win a trade.

MID-LATE GAME

While playing the mainly AP build, be sure to engage with Shurelya's and W + R for flashy and fast plays. But when playing the tanky build, i suggest popping Redemption while you engage so your team can follow up safely with you. Zeke's will empower autos from your chosen partner and you will slow enemies when using your R.

Diving towers is something i dont suggest if your R is on cooldown. But when it isnt, you can dive and run out of range after tanking maybe 1 or 2 hits so your team can follow up for a kill.

Charming AP Rakan
This is the ideal build for the most damage on engage. Your W AP scaling is huge towards late game with insane healing ratios on your Q with tons of AP. On top of that, Absolute focus will grant big amounts of AP while above the 70% health mark which is great when building items like Redemption and Morellonomicon!

Situational AP Items
Banshee's Veil is perfect for hard engage with the temporary black shield, letting your avoid incoming roots and stuns while diving the enemy team. Rylai's is another fantastic item for health, AP, and slows while engaging on Rakan. Most of the other items are very self explanatory.

Buff daddy tank Rakan
Tank Rakan is great peel and a damage absorber with Guardian and his E shield. Using Q with some mild AP ratios and his revitalize rune is great for poking and healing your team on-top of a Knight's Vow.

Situational Tank items
Again, most are self explanatory. More armor and magic resist, more health, you get the idea.