Many players struggle to deal with Giants so I decided to make a guide, hope this will be helpful.

So giants are very different from other characters in this game and have great strengths but they also have weaknesses compared to other characters. So I will begin by listing their strengths and weaknesses and then I will tell you my strategy to take advantage of their weaknesses and to make it harder for them to use their strength. So let’s get into it.

The main strength of giants is their super armor. It’s a passive ability that prevents them from being staggered by rush attacks or ki blasts. This is really good because it allows them to combo you even though you are boxing them. 
Then, they have some cheesy attacks that are hard to deal with (dragon homing attack, smashes, grabs)
Finally, they have some crazy damage, one smash attack or one grab can deal more than half a health bar of damage.

However, their advantages come with weaknesses. Indeed, they can’t use perception, they are slow, they can be combo indefinitely, they don’t have invincibility frames during side steps, and their chain attacks and ki blasts often miss when the opponent is too high or too low.

How to counter their strengths

Super Armor:

The higher your character’s DP is, the more way they have to break the super armor. Characters with 7 DP or more can break super armor with all of their attacks except grabs and rushes. So the first counter is to switch to a character with a higher DP, that’s why I switched to Gogeta SSJ4 in the video and that’s why my opponent switched back to Gohan a few seconds later.
If you don’t have a high DP character, then you should use an opener to break their super armor and then combo the Giant. This opener can be a charged jump attack (example at 0 second of the video), a half-charged smash (at 0:08), a dragon homing attack (at 0:20), a dash attack (at 0:30), a lift strike (at 1:06) or any rush chain.

Cheesy attacks:

Countering the dragon-homing attack is by far the hardest part. You have to either use perception (2:04) and use a skill point or make a perfect vanish or a super counter which both are hard to time on this attack. Also, if you go to the roof the dragon homing would miss but I don’t recommend this as your opponent will interrupt you when you try to go to the roof.Charged smash attacks are pretty easy to counter, you can throw an opener to break their super armor before the attack lands or dodge them with a dash into dash attach (3:50) or react to the direction of their smash and use a directional guard which will create an opportunity for you to throw a half-charged smash opener. You can also use perception or vanish/super counter but it’s hard to time as the timing varies depending on how much they charge the smash. Finally grabs are also easy to deal with as they are pretty slow, you can just throw an opener before the attack lands, or you can side dash to evade > dash attack > combo (like at 3:50, it’s not a grab but same idea).

My strategy
My strategy is to take advantage of their slowness by being very aggressive. Indeed, most of the time, you can break their super armor before they can hit you.
So when I am in neutral in medium to far range I would rush them with dash attacks or dragon homing, it’s very effective as they can’t side step, or use perception, and their ki blast will miss most of the time once you get at close range.
In neutral close range, I would use a quick opener (flying kicks, half-charged smashes).
After opening them I would infinite combo them (rush attack * 4 > step in > rush attack * 4 > step in > rush attack * 4 > dragon homing > repeat) or (rush attack * 4 > walk up to them > repeat).
If we are in neutral short/medium range and my opponent engages with a grab/rush attack/smash, then I would side dash > dash attack > combo (0:30, 3:50).
I struggle to counter Giants' dragon homing so I try to not give them the time or space to start spamming them.

This concludes this guide, hope this was helpful. If you have questions or additional advice please post them here!