Currently, it's set out like this:
John "TRICKSTER" Egbert pilots an IPS-N Tortuga called Prankster's Gambit. It has the ISP-N Raleigh's Kinetic Hammer. I chose this mech largely because John has absurd levels of MANGRIT and is very protective of his friends.
Rose "THERAPIST" Lalonde pilots a HORUS Pegasus called Thorn of Oglogoth. It is the only one currently installed with an NHP, a SISYPHUS-class named Jasper. I chose this mech for largely the same reasons you did.
Dave "GODHEAD" Strider pilots a HA Tokugawa called Ill Beats To Study To. This is my least favourite choice, but it was basically the default choice after all the others I'd chosen. I'll go into more detail down the page.
Jade "GNOSTIC" Harley pilots an SSC Death's Head called Dreaming Dark. I chose this largely because Jade's Strife Specibus for the vast majority of Homestuck is RIFLEKIND and it makes sense as a pure sniper build.
So Homestuck is very heavy on 2-fold and 4-fold fold numeric categorization of sburb session players.
There's 2-fold numeric categorizations - male/female, Prospit/Derse, red/blue (troll session), red/green (Cherub session), active class/passive class etc. and also dualisms such as Time/Space, Light/Void, Heart/Mind etc.
There's additionally what I would pretentiously describe as dualistic parallelism between scratched timelines: John (GT) and Jade (GG) become Jane (GG) and Jake (GT), exchanging both abbreviations and genders, while Rose (TT) and Dave (TG) become Roxy (TG) and Dirk (TT), exchanging abbreviations but not genders. We can speculate a similar thing may have happened with the pre-Scratch trolls but Hussie never bothered to tell us what their trollhandles were.
There's 4-fold numeric categorizations, such as classical element (Earth/Air/Fire/Water), noble gas (Helium/Neon/Xenon/Krypton), exile (WV/AR/PM/WQ and CD/HB/SS/DD), consort type (turtle, salamander, crocodile, iguana, etc.)
(The trolls also had 12-fold numeric categorizations but fuck that it's too complicated to categorize and not relevant right now)
Lancer conveniently has a couple of very useful 4-fold numeric categorizations: manufacturer and HASE (and it's nested, because the manufacturers themselves divided by HASE). It follows that I should divide the four original Homestuck kids one-per-manufacturer.
I had to give John the giant hammer and a big strong mech. If we're assuming that he's LL6, I reckon he has two levels in Tortuga, three in the Raleigh and a single LL-splash in Blackbeard for Synthetic Muscle Netting, to make his Tortuga e%tra STRONG. For core bonuses, I'm pretty sure he has Gyges Frame (more Threat with his hammer!) and Improved Armament.
Rose has all three levels of Pegasus, a level of Swallowtail for Lotus Projector and I'm not sure where her other two levels are. Her Core Bonuses are Lesson of the Held Image and Universal Compatibility, which she uses SISYPHUS dice-manipulation to rig so she always gets her Core Power back.
Jade has all three levels of Death's Head, two levels of Mourning Cloak for Singularity Motivator and one level in the Sunzi for obvious reasons. Her core bonuses are Auto-Stabilizing Hardpoints (on her Railgun) and Overpower Caliber (also on her Railgun).
Dave got stuck with a Harrison Armory mech mostly to maintain Homestuck's numerology. While the Blackbeard, the Atlas and the Metalmark all fit him, it would not be in keeping with Homestuckian numerology to give him a mech from a manufacturer that someone else had. Also, giving him the Tokugawa and making Engineering his highest stat at least let me keep his fire motif intact.
I reckon Dave has all three ranks in Tokugawa and three ranks in the Sherman for Redundant Systems Upgrade and potentially ASURA. His core bonuses are Superior by Design and Heatfall Coolant System because he stays chill 24/7.
TG: yeah dont worry i fully acknowledge superior by design is a hella fashy name
TG: but ill burn in the fires of unironic double hell before i spend a single turn impaired