Splasher

I will put this at the top, this site will pretty much help you with everything you need for this achievement : https://www.speedrun.com/Splasher
There are videos for every levels, every speedruns, different runners, etc...

To unlock this achievement, you need to get all platinum medals the game has to offer, there are 25 of those, one for each level and one for each speedrun.
There are 22 individual levels and 3 speedruns ( Selfish, Standard, Gotta Catch'em All ).

Obviously you want to start with the individual levels to get familiar with them before starting any speedrun.
You can't see the platinum cut-off in game until you beat the said time, so I will put them down here :

Time Attack :

1. Welcome to Inkorp : 01:37:70
2. Potatoes Ink : 01:29:02
3. Stick To The Plan : 01:33:51
4. Let It Bounce : 01:26:60
5. Jump On The Water : 01:08:35
6. A Bad Encounter : 02:31:28
7. There Will Be Fries : 01:48:69
8. Ray Man Origin : 01:50:37
9. Stick On The Water : 01:36:86
10. Ink In Park : 01:35:46
11. Wink Walker : 02:05:55
12. Troopers Please : 01:58:59
13. Water Is Coming : 02:16:28
14. Inkorp Express : 02:27:49
15. Big Bounce Theory : 01:21:27
16. Toxink Bubbles : 01:21:23
17. Storm Wind : 02:00:12
18. Ray Man Legend : 01:39:19
19. Toxink Avenger : 01:50:35
20. The Glados Principle : 01:14:15
21. Apocalink Now : 02:03:95
22. Good Luck Splasher : 03:50:41

Speedrun :

Selfish : 43:44:48
Standard : 50:50:88
Gotta Catch'em All : 73:40:57

You may wondering, what's the difference between these 3 ?

Selfish : Complete the game without collecting anything, straight from point A to B, you don't have to go back in the hub between levels.
Standard : You must collect 80 splashers by the end of the level 21 to unlock the final level, you will have to navigate in the hub between levels.
Gotta Catch'em All : Basically a 100 % run, you need to collect every splasher, you will also need to navigate in the hub between levels.

I'd recommend to do them in the order listed above.

Overall tips :

- This one is a personal one, but if you do read and do this before even starting the game, I believe it can be very useful, with the button mapping on your X1, switch X to RB, it's just so convenient to spray water with a RB, you can kill enemies while jumping, open doors while moving without moving your fingers, just overall a better and smoother experience than using X, it will help a lot for the platinum medals.
Pin the button mapping page to your xbox one dashboard, so you don't have to mess around in the settings everytime you want to play splasher and switch back to play another game.
- Try to jump whenever you can, it's faster that just moving forward.
- I didn't know about that until yesterday, so it's not like you really need to do this, but by pressing down on the stick or d-pad you fall faster than without touching anything.

Full game speedrun tips :

- Only go for a shortcut if you can hit it consistently, it's not worth it to try a shortcut to save 1 sec with a 50% successful rate, even more before a checkpoint, you will just lose time in the end.
- Take your time sometime if it's possible.
A quick exemple : at the end of the level 17, if you shoot the bull by accident while jumping from the wall, you can hit him in mid air and die, this will cost you around 30 sec.
So when in sight, stop on the wall, aim to him, shoot him with a drop of yellow paint, let him die and you are good to go.
Apply this to pretty much any situation you're not 100% comfortable that can cost you a lot of time when there is a safest strat.
- For the first few runs, do not restart becaure you died a couple of times, you need to build consistency before having the luxury to restart after your screwed up.

I would also like to add, after you're done with the individuals levels, there is a good chance you'll approach levels in a very robotic way, if you were off pattern in an individual level, you would just restart, no big deal, but in the speedrun when you are off pattern, if you don't know how to deal with it, you will die, it's especially true for the levels 16,19 and 21 with the acid drops. I'd recommend to mess around in these level for 30 m or so, stay on the walls a bit longer than usual and try to jump between the drops, collect splashers, etc..
You want to be able do deal with any situation and don't be in panick mode because you didn't meet these situations before.

If you have any questions, don't hesitate to comment, I will try my best to help you out.