HE Shallot LGT is highly versatile in his Damage output but fits especially well in Saiyan Teams. As expected from a Story Mode protagonist, this Fighter is good but not great. He provides a lot of Team Support through his Main Ability and his Z-Ability is an uncommon Health Boost--although it isn't as strong as EX Raditz BLU's.
HE Shallot LGT has an additional quirk: He’s able to learn Special Moves from other Fighters. This means that after Friendship Rank with a Fighter reaches level 2--and their Move is Tagged as Teachable--HE Shallot LGT can use that Move, making him even more versatile.
However, with his poor Damage output, HE Shallot LGT is mostly a Support/Bench Fighter in PVP, so wasting a Special Move Art Card with him is probably not going to be used much against other Players.
Useful against Dark Element Bosses in Story Mode
Being the only Fighter with the LIGHT element, Shallot can find a place as Main Fighter in all the Matches against Dark Enemies. It’s not mandatory, but it helps a lot if the other Teammates are under leveled.
There are also many Challenges that require he Fight or use a certain move during the match, so keeping him leveled up is a great way to gain Chrono Crystals.
This Saiyan can come in handy as a Support for other Fighters thanks to his post-transformation Main Ability, which applies a 20% increase in both Strike and Blast Attack for all Teammates, while at the same time recovering 25% of his own Health.
A good thing to note is that he isn’t a Blast or Strike-only Fighter, despite being listed as a Melee-Type Fighter.
Both of his Attack stats are almost the same, allowing to use both Blast and Strike Art Cards in the same way, which is great for beginners like every good starter should be.
His Attack stats are low average, so unless he's being used in Story Mode, he should probably stay on the bench.
It's pretty strange that the Main character of story mode would have so few Equip options to chose from, and yet he does. What's worse is that the Equips he can use are fairly old and no longer that good by PVP standards.
Shallot can be run as a Bench fighter in Saiyan Teams, however, he's more of a backup for Players who don't have better Fighters.
His Super Saiyan Transformation gives him a bit of an edge, but not enough to make him truly competitive yet.