Cho'Gath is indeed a unique tank with high durability and a powerful ultimate that scales off his HP, making him a strong threat in late-game fights.:

Strengths:
Tank Scaling: His passive HP scaling means he naturally becomes tankier as the game progresses, especially when stacking his ultimate. This makes him a hard-to-burst tank who can sustain well in fights.
Ultimate Burst (R - Feast): His ultimate deals true damage based on the target's health, making it excellent for securing kills or objectives. It also counters Smite if timed correctly, giving him some utility in securing Baron or Dragon.
Strong Lane Phase: In lane, Cho'Gath can be a bully, especially against melee champions. His sustain from passive makes him resilient, and his E (Vorpal Spikes) punishes enemies who try to trade with him in melee range.
Good Crowd Control: His Q (Rupture) and W (Feral Scream) provide strong AoE CC, and his silence can be valuable for locking down carries or interrupting critical abilities.
Weaknesses:
Countered by %HP Damage: Champs like Vayne or Kog’Maw who can deal %HP damage can bypass his tankiness, making him more vulnerable.
Low Mobility: Cho'Gath is slow and lacks dashes or gap closers, so he struggles to catch mobile champions or escape when focused.
Predictable CC: His Q has a long cast time and is easy to dodge, especially for champions with dashes or high mobility, so landing it requires prediction and good timing.
Reliance on Positioning: Cho'Gath needs to be close to enemies to fully utilize his abilities, making him vulnerable to kiting.
Tips to Succeed with Cho'Gath:
Build Tanky: Maximize his strengths by going for tanky items. His damage will still be sufficient even with a tank build.
Target Priority: In team fights, aim to crowd-control (Q or W) high-priority targets, and look for opportunities to R (Feast) a carry. Even if you're building full tank, Feast provides strong burst.
Combo Execution: Landing a successful combo requires predicting the enemy's movements. Start with E to slow and follow up with Q for the knock-up. Once CC’d, continue applying pressure to keep them locked down.
Target Selection: Cho'Gath shines against immobile or slow-moving champions. Against mobile champions, focus on peeling for your team or controlling the frontline.
Overall Strategy:
Play around objectives and team fights where Cho'Gath can make use of his CC and tankiness. Timing his Feast to secure objectives can turn fights in your team's favor, and his ability to stay in fights for extended periods makes him a valuable tank for the team.