If there's a sufficient amount of cover for your guardsmen, they will be incredibly hard to shift. You're going to have to make up for a mobility deficit with other formations, like stormtroopers and valks. I'd keep one of those companies in chimeras for the reg HQ. You'll need their mobility and the re-roll of the SC.

EDIT: so successful? A conditional "yes"

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Let us playtest like the Greeks of old... You know the ones I mean

As CP says, if you remember to keep them in cover and mutual support range they can be very hard to shift, but you will still need to bring along some of the IG 'big toys' to provide appropriate support for the grunts.

It's worth mentioning that the Cadian army list has better tools in it for an infantry focused list.

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Currently doing a plastic scenery kickstarter

Personally I prefer tanks to infantry (easier to paint with my poor eyesight) so I go for minimum infantry and mechanised where possible. However opponents have regularly used footslogging infantry as both SL and Cadian- if those grunts get into cover they are hard to shift.

Also helps with activation count- as infantry companies are cheaper than mechanised and tank companies, you can spend more points on the fun stuff.

Cheers

James

Mutual support means that they should be at least within weapons range of each other, and preferably within support fire range (but not intermingled), so if one company is attacked, it's neighbors can counterattack.

The idea is to keep your opponent from isolating the formations and defeating them in detail.

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SG

Ghost's Paint Blog, where everything goes that isn't something else.

Two things: I'd replace one of the FS upgrades with a sniper so you can take a hydra with the mech company, and I wouldn't count on overwatch providing enough cover for a guard company. Real terrain is your friend. On mutual support, SG is right. It's almost important as the cover bit.

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Let us playtest like the Greeks of old... You know the ones I mean

It can get tricky, yes, but note SG said "within weapons range" as well. So that gives you a little more flexibility as with IG you're talking 30cm (for snipers to be included) to 45cm.

I always feel uncomfortable when my IG has fewer than two hydras in it. Relying too much on t-bolts can get problematic when they have BM's later in the game and/or the opponent has equal or greater numbers of aircraft. Looks like a good list otherwise... reminded me that I should try warhounds out with my IG sometime...

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Let us playtest like the Greeks of old... You know the ones I mean

I took six hydras and a pair of t-bolts at full scale assault recently and I just about scraped through.....

I'd swap one t-bolt formation for a hydra battery, excellent AA and AP firepower, and if they survive (always worth having a commissar in one) they're fast enough to contest the blitz with a timely march

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Just some guy

My hobby/painting threads

Army Forge List Co-ordinator

I may be mistaken but around ten lists were marines, most with several thunderhawks flapping about the place.....

in my three games I had a warhound blown up by marauders and my BTS was broken by a vampire full of aspect warriors..... par for the course really....

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Just some guy

My hobby/painting threads

Army Forge List Co-ordinator

So it looks like the formations in your army will be working in pairs; 2x companies and artillery to control the Blitz and one or both objectives in your half of the table, two mechanised companies and warhounds working in your opponents half. So, my suggestion would be to drop the FS upgrades and get a hydra battery to be placed between and behind the Infantry companies, and use the remaining 50pts to put a Hydra on the mechanised company. That way you would get good ground AA cover for all the formations and an extra activation to boot, and the Hydra Battery can potentially act as an objective grabber in turn #3. It also means you are less reliant on the TBolts for AA, which in turn frees them up to harrass ground targets, especially broken enemy formations.
(Note, putting a Hydra upgrade on an Infantry company does not really work if it is the only AV target in the fomation as it would soon get killed by any AT fire).

And as for strategy and tactics, keep it simple - make the terrain work for you (you will need to ensure you have a decent amount of it ~30% coverage is the recommended level). Mutual support has been covered by others except to say that it is true for most formations in E:A; you need to get the different formations to work together to achieving your strategic aims.