The terms Alchemy and Renkin are used interchangebly.

SP

Renkin can achieve 4 levels of SP (Style Powerup).

All hunting styles have access to SP 1 and can only set 1 HA to SPHA. While Renkin can go up to SP4, and Renkin can set all 3 HA to SPHA.

According to the official page

• SP 1 (Yellow) Power up each style differently
• SP 2 (Orange) 1 + Stamina gauge takes longer to reduce its max size
• SP 3 (Red) 1 + 2 + auto health regen
• SP 4 (Purple) 1 + 2 + 3 + More stagger (I think)

And HA set to use SP will charge slower (by u/Ivalia)

Renkin & SP

When you transmute different items, you will upgrade your SP level; but it will not replace your current SP, not until you reactivate another SPHA. For example, currently I have SP2 active, I transmute an item with my renkin barrel and gain SP3, all my SPHA will switch from orange highlights to red highlights, but my SP2 remains active. SP3 will activated whenever I activated the red SPHA.

Many thanks to u/ivalia for figuring out the mechanics. You need to spent a certain amount of gauge to upgrade your SP.

Total Gauge spent	Sp level gain
2	2
5	3
12	4

My test cases (referring to the item table below, 3A is level 3 transmutation with A button)

• 3A (SP2) + 1A + 1A (SP3) + 2X + 3X + 3A (SP4)
• 3A (SP2) + 2X (SP3) + 5X + 1A + 1X (SP4)
• 2X (SP2) + 3A(SP3)

Renkin item list

Source + in-game description

Level	Button	Item	Effect	How to use
1	X	Renkin Food	Restore small amount of stamina	Use from pouch
1	A	Renkin Whetstone	Whetstone for BM. Increase HA charge rate. You get 1	Just like a normal whetstone
1	A	Renkin Ammo	Ammo for LBG/HBG, Increase HA charge rate	Load it the same way you would load ammo
1	A	Renkin Coating	Bow Coating for Bow user. Increase HA charge rate	Use it like a coating

Level	Button	Item	Effect	How to use
2	X	Immunizer	Slow auto health regen	Use from pouch
2	A	Sonic Barrel	Generate small noise in barrel (or it could simply a visual effect). Launch a standard sonic bomb when activated again	Use from pouch. Y to pull out a barrel, Y again to release a sonic bomb

Level	Button	Item	Effect	How to use
3	X	Earplug	Essentially the MH4U emergency earplug item	Auto applied when it is transmuted
3	A	速振薬	Increase renkin gauge charge rate. Change your renkin gauge to white. Faster renkin shake and transmute.	Use from pouch

Level	Button	Item	Effect	How to use
4	X	フエール	Unknown. Description says it can combine with other renkin items	Unknown
4	A	Bazooka	Big slow boom, in an arc, off a barrel. You get 2 from a single transmute.	Press Y to use

Level	Button	Item	Effect	How to use
5	X	気合玉	Increase HA and prowler support gauge for those in close proximity. AOE range similar to a deodorant	Use from pouch
5	A	Healing Barrel	looks like a small health over time while you are holding the barrel (or it could simply a visual effect). Large heal and cleanse when activate the barrel	Y to pull out a barrel, Y again to activate

Weapons

Short summaries on major changes in moves.

Greatsword

• No strong charge slash
• A+A will give you a side slash + strong charge slash finisher (but I don't think it will have the MV or power of the regular version

Longsword

• X for normal attacks
• A for fade slash
• R for spirit combo, you cannot sneak in X or A for additional attacks
• No fade slash -> spirit

Sword and Shield

• No backhop
• Basically Striker, with 1 or 2 missing move, but the combo tree is pretty much still intact

Dual Blade

• No spinning demon slash, we are going back to the normal run-in scissor slash.

Hammer

• No lv3 spinning into super swing, just super pound
• Basically Guild without the spinning thing.

Hunting Horn

• No neutral XA backslam.
• XA backslam is only accessible by doing XA (super pound) -> XA (backslam)

Lance

• No counter
• You can do R+X (guard-poke) -> X or A -> X or A
• You can do shield-advance with forward+RX or forward+RA

Gunlance

• No charged shot
• Faster Wyvern fire
• No X>X>XA (upswing), or X>XA(upswing)

Switch Axe

Sword Mode

• A (side slash) > X (morph, axe-side-slash)
• A (side slash) > A (double cross slash) > R or X (morph, axe-side-slash)

Axe mode

• X (overhead slash) > R or A (morph, sword-overhead-slash)
• X (forward thrust) > R or A (morph, sword-overhead-slash)
• A (side slash) > A (forward thrust) > R or A (morph, sword-overhead-slash)

Charge Blade

Sword Mode

• Pressing XA will do a auto AED-into-shield charge. No shield will charge to yellow shield. Yellow will charge to yellow. Red charge to red.
• Holding A will auto release when it hits the optimal timing

Axe Mode

• No ultra AED, XA will do AED 3.

Insect Glaive

• No infinite combo, it is either X->X (finisher) or X->A (finisher)
• No A backflip
• No kinsect charging

Light Bowgun

• 2 maximum side-step/back-step

Heavy Bowgun

• No siege

Bow

• B (back-step) -> B (back-roll) -> R (charging)
• No powershot, only curve shot