Yes, it is true that you can get 50 BP in a single Mantine Surf session, but you need at least 145,000 points to do so. The difficulty and length of the surfing minigame depends on which island you take off from (as far as I can tell, the destination island doesn’t matter). After around the 80,000 point mark, the number of BP you get increases exponentially, so you’ll get more BP if you take a long route and earn 100,000 points than if you take a short route twice earning 50,000 each. Because of this, setting off from the later islands is better so that you can have more time to earn more points. I personally go between the second and third islands (Akala and Ula’Ula) when I’m grinding for BP, because the number of obstacles on the fourth island tends to prohibit my progress to a frustrating degree, but you could in theory get the most points on Poni Island, so feel free to try there if you’re confident. Here’s what I recommend for when you’re actually surfing:
- Never jump off the wave unless you’re at the maximum momentum (or if you’re desperate to get away from an obstacle). This gives you the most airtime to get combos. You can generally fit one 4-move combo and another 3-move combo in to a single jump if you’re quick about it.
- Always get the landing bonus. Not so much because the points are that great, but because you get to keep a lot of the momentum, which makes it a lot easier to get back up to top speed and maximize your airtime.
- The best opener. Whenever I’m surfing, I always open up my first two jumps the exact same way. Build up enough momentum, jump, use Magikarp Splash (a hidden combo that activates by doing any four move combination that doesn’t result in another combo), then either Lanturn 360, if jumped from a high wave, or Primarina Twist, I’d jumped from a low wave. Land, build momentum again, then use Over-The-Gyarados and Lanturn 360 / Primarina Twist (depending on wave height, again). This gets you a total of about 20,000-25,000 points in just two jumps. You don’t have to do these two at the start (that’s just what I like to do), but you do want to do them back to back to get the best score, since Over-The-Gyarados works by doubling the score of your last jump.
- Follow-Up. Since both Magikarp Splash and Over-The-Gyarados give really low scores if used more than once in a session, just use Starmie 720 and either Lanturn 360 or Primarina Twist on all of your jumps after the opening.