Since it's been 3 years since the last GLT, which provided Malmir's lizardmen with an amazing Skink Fanatic and a short-lived Skink Looney, the rules have changed and so it's time to update my previous GLT weapons rundown, race by race. Most races have G-only linemen, but BB20 gives you the option to save for stats and secondaries, which leaves us with fairly obvious paths for most of them.

Block/dodge/MB/+MA on your ball and chain, with strip ball and tackle still interesting depending on how you intend to use them.
Block/Dirty Player/Sneaky Git/Pro on the chainsaw, and probably a bog standard sacker build for the pogo. The bomber is not available this time, as the rules for the GLT were finalised before the latest FAQs were published. I'll still include it at the bottom of each list, just in case next year's GLT is different.

The most important thing seems to be to choose linemen that are banking some SPPs so you can skill them up right after choosing the weapon.

Any of the 28 teams might have different overall synergies with the various secret weapons in terms of how much they can stall and consequently how long they can keep the SWs on the pitch.

Amazons
1) Ball and Chain. You start with dodge, so after block you should probably start saving for doubles and stats earlier. Powerful piece complementing your 2 blockers in moving the ball forward, denying space and opening pathways.
2) Chainsaw. Like a goblin chainsaw but starts with dodge, G access and higher strength. Yes please.
3) Pogo Stick. Leaping on an unmodified 3, wrestle/tackle/strip ball/frenzy access, just needs saving for a lucky +AG to become a truly amazing sacker. Works miracles for your Roxana withdrawal symptoms.
*) Bombardier. PA4+ and no P access. Sad.

Chaos Chosen
1) Ball and Chain. Block, Claws, Mighty Blow, Stand Firm, Tentacles, Guard maybe? Anybody who's played Pestilens in Secret League knows what a tentacles Ball&Chain player can do. Probably the one fanatic that helps the most on defense.
2) Chainsaw. Two heads and break tackle for cage dives?
3) Pogo Stick. Remember when you rolled a double and picked leap because it sounded fun, and then used up another skill to get VLL and then had to build the whole sacking stack on top of that? That never happened because you took dodge or leader, or the guy died early. 3+ unmodified leap with horns is quite good, actually.
*) Bombardier. PA4+, but the Beastman has P access! Not enough, probably, to make you pick it over the above 3 fantastic options.

Chaos Renegade/Khorne
1) Ball and Chain. Refer back to the Chaos Chosen entry above, it even costs 10k less (Horns/Frenzy are useless to the Fanatic anyway) but the lack of S access on primary makes it harder to build up to perfection.
2) Chainsaw. Refer back to the Chaos Chosen entry, only 10k cheaper for no particular disadvantage, or loss of armour in the case of Khorne.
3) Pogo Stick. I would say that it's the same as the goat above, but without horns, it will take just one more skill to make him a monster sacker. Khorne Pogo opens up some crazy options, too.
*) Bombardier. PA4+ and no P access. Sad.

Dark Elf, actually, Any Elves, really
1) Ball and Chain. The first one we see with GA access. Blodge then MB then stats for movement. Probably changes the timings of when you score and how you setup. Might not sync well with the rest of the team, as their offense doesn't exactly need a piece like this.
2) Chainsaw. SG/DP still an option but the nerfs make it less safe of a choice.
3) Pogo Stick. 2+ leaps? Yes please!!
*) Bombardier. Only PA 4+ but with PA access. It could work, sometimes.

Skaven
1) Ball and Chain. G access as normal, but needs some S/M secondaries in order to become a proper monster. Not sure if a MA3 player works well with a team that is running around a lot.
2) Chainsaw. Rats really should have a chainsaw star player. And by star player I mean Dirty Player.
3) Pogo Stick. This is really good, no question, considering the fact that it won't be sent off. Make him your sacker and save those precious Gutter Runners for retrieval duties. It will also cost much less than your tooled up GR.
*) Bombardier. It could be useful on defense, I'll give you that. Not the best especially with that low armour and PA4+.

Chaos Dwarf, Humans/OWA, Imperial Nobility, Norse, Vampires, Orcs
I'm putting all these races together even though some might have higher chances to survive for longer, as the development options are the same.
1) Ball and Chain. Still a solid choice, slightly weaker than the above races. The Norse one even starts with block.
2) Chainsaw. A brilliant fouler, cheap and effective. The Orc one can probably survive most kickbacks, especially if it can save up for cheap +AV.
3) Pogo Stick. Same G access sacker as the others, but with no dodge/horns/whatever on top to make it stand out. The Nobility peasant has 4+ leap so probably even worse than the Nurgle one.
*) Bombardier. PA4+ and no P access. Some even 5+. Super sad.

---teams above, except Nobility, can get something out of every combination of any two picks, teams below should probably go for fanatic and saw; not many would pick the bomber now even if it was an option---

Dwarf
1) Ball and Chain. Block, Tackle start with S access really makes it interesting. That lino didn't even become noticeably slower and really makes your offense better, great cage corner on offense, or possibly a great roadblock against a slow opponent on defense. If you have a Deathroller as well, you can do a tag team or keep one per half.
2) Chainsaw. Reasonably priced and non-loner version of the Star Player whose name now escapes me. Probably because nobody ever took him. You can get +AV and pro, even.
3) Pogo Stick. This is probably the first time the Pogo looks less appealing than the other choices. I get the wildcard appeal, but are you really going to try and roll that 4+ Leap and probable GFIs due to low M, when it comes to it?
*) Bombardier. Eziasson's son only has PA 5+ but as a "rostered Cindy" with actual armour on, it could have a role... Next year!

Stunties (Ogre, Snotling, Goblin, Halfling) + Black Orcs
1) Ball and Chain. Right Stuff doesn't work anymore with ST4+ players in BB20. Still, starts with dodge and has secondary access to most skills needed (except gnobs/snots who lack S access)
2) Chainsaw. Love it, very stunty. BTW, also still Right Stuff.
3) Pogo Stick. Not sure what use you could make of it but it could save you some dodges in desperate situations.
*) Bombardier. Apart from a Snotling team wanting to have 3 for some reason, now that you can only throw one bomb per turn there's little need for it. Cindy is still available to those without a rostered bomber, too. Except BOBS, bobs might want this.

Tomb Kings of Khemri/Shambling Undead + Necromantic Horrors
1) Ball and Chain. The new skilling system makes it interesting. Regen could also keep him alive for longer.
2) Chainsaw. Yes please!!
3) Pogo Stick. Even funnier than the Dorf one. At least he's cheap! Don't bother.
*) Bombardier. PA6+, or even nothing on necros. And no PA access.

Lizardmen
1) Ball and Chain. Similar to the Stunty teams option.
2) Chainsaw. MA8 saw will make people hate you. Sneaky git nerf means it might need additional protection to avoid being blitzed and removed.
3) Pogo Stick. You could argue that 3+ leap sometimes is better than having to dodge through the screens.
*) Bombardier. PA 4+ and no PA access and Stunty. Not ideal.

Nurgle
1) Ball and Chain. GM access gives you a piece similar to the Chaos teams. Lack of S access makes him work harder for certain parts of that stack. Bring back Tolly!
2) Chainsaw. Do take this.
3) Pogo Stick. Similar to what we said about the Undead ones, minus the regeneration. I wouldn't bother.
*) Bombardier. With all the Disturbing Presence, it should be almost impossible to intercept it on anything but a 6. But you also have PA6+ so...

Underworld
1) Ball and Chain. Combine what you can do with a Chaos Renegades/Nurgle ball and chain, with free Dodge. Pays a bit more for G skills though.
2) Chainsaw. Right stuff, 2 heads primary access, break tackle secondary access. Sounds fun!
3) Pogo Stick. It could be useful, when surrounded, but why are you carrying with a goblin?
*) Bombardier. Decent enough. Maybe you miss Dribblesnot. There's always next year.


Note/TL;DR
Grotty's Little Tournament allows the winners to picks 2 out of 3 "secret weapon" options, on 2 unskilled linos. The options are Chainsaw, MA3/ST7/Ball&Chain, Pogo. Apply, and you may get them!

EDIT dentface spotted the fact that in BB20 right stuff is useless for ST4+ players, thanks! edited in, credit to him :)